Course: ID PASC

Star formation across the Universe occurs mainly in massive stellar clusters forming at the densest and coldest regions of giant molecular clouds. This mode of star formation has a wide impact on a wide range of scales, from local effects on the evolution of protoplanetary disks and local ISM, to global effects affecting galaxy populations and evolution. Yet, we know very little on why the clustered mode is the one favoured by nature. Two factors contribute to this: a) there are too few comprehensive observational studies of massive stellar clusters, as they are typically distant and embedded in placental material, and b) theory and simulations are difficult to undertake due to the large dynamic range needed of the physical variables (density, size) and because radiate feedback in a highly structured ISM is very challenging to model. The most fruitful way to make progress in the field is to acquire better observational data from top instruments on world-class observatories, to be able to characterize the poorly constrained properties of the emerging stellar clusters.

This PhD thesis proposes to advance the current state-of-the-art by combining cutting-edge observations from the leading world telescopes – the ESO Very Large Telescope at Paranal Observatory, with the newest VLT instrument, the Multi Unit Spectroscopic Explorer (MUSE). Existing deep, high-resolution near-infrared and infrared observations of massive stellar clusters emerging from giant molecular clouds (ages 1-5 Myr) will be combined with new MUSE panoramic spectroscopy in the visible. Ancillary ESA Herschel data on the dense placental ISM involving these clusters will also be analysed. This unique dataset - only possible to obtain now - will allow for the first time for a combined characterization of the stellar spectral energy distribution with visible line emission diagnostics of the stellar population in the cluster and associated ionized gas, resulting in a robust study of all the properties that are critical to guide and constrain our understanding of clustered star formation: cluster ages and age spreads, Initial Mass Function, protoplanetary disk evolution in massive clusters, impact of early supernovae, cluster and gas dynamical state and cluster dispersal into the galactic field. Ultimately, the foreseen characterization of the most massive clusters in the Galaxy will provide crucial constraints to the impending generation of theoretical and numerical models.

The candidate should have an interest in observational astronomy, ideally with scripting/ programming and statistics skills. The candidate should be available for observing runs in leading edge observatories and missions with collaborating institutions (CENTRA and João Alves lab at University of Vienna).

The solar atmosphere (namely the photosphere and the chromosphere) has been extensively studied on the aim to understand physical phenomena as the convection and the solar magnetic field. To understand those is crucial to know about the solar activity and his causes.

At the Geophysical and Astronomical Observatory of the University of Coimbra we have a large data base of more than 30000 solar images.
With more than 80 years of observations, since 1926, a local spectroheliograph acquires sun digital images in three wavelengths bands (Halpha, K1-V and K3) every day including weekends and holidays. Data acquisition averages more than 300 (clear sky) days per year. All old analog photographs have been digitized. For each day we have images of the photosphere and the chromosphere and the consequent features of interest (sunspots, filaments, flares).

So the idea of this project is to build a semi-empirical model of the solar atmosphere crossing the data acquired in Coimbra with MHD simulations in order to the internal structure of the atmosphere, this means for example, the internal profile of pressure, temperature and density.

This work will be a combination with image recognition methodologies (using the mathematical morphology operators) and the MHD simulations.

The Jovian system is known to be outstandingly complex with its extremely hazardous and highly
dynamic radiation environment. Therefore, its rigorous, accurate exploration, as well as profound understanding is enormously valuable for answering questions on planet formation and emergence of life. One of the biggest challenges for the ESA JUICE mission, is to measure and handle the compound, intense and highly penetrating radiation environment of Jupiter and its active moons. Based on previous data, it has been long understood that Jupiter radiation field plays a decisive role in radiation damage scenarios for the whole spacecraft and all its payloads. Due to its excessive features such us very high fluxes and wide range of energies, it also drives detection principles for science instruments and in particular for radiation monitors. In this context, a comprehensive, reliable and accurate monitoring of the radiation onboard of the JUICE mission is a major challenge and a high priority task. It is crucial for safe operation and continuity of the mission, as well as for the scientific data analysis support.

RADEM is the Radiation Hard Electron Monitor, for JUICE, the next European Space Agency Large
mission, which will be heading for JUICE in 2022. It is being developed by an international consortium, lead by EFACEC, and in which LIP, PSI(ch) and IDEAS (no) take part, under a contract with the European Space Agency. In the current phase of the development of RADEM, which started in May 2014 and will contibue untill September 2016, its design concept will be further optimised, and the detector will be calibrated and tested.

RADEM is based on a design concept for which a first prototype already exists. The first design concept included an electron detector, the Magnetic Spectrometer (MS) and a proton and heavy ion dedicated sensor, the HEP. Given the dynamics of the Jovian magnetosphere, both the MS and HEP will hardly have their pointing directions aligned with the Jovian magnetic field. Moreover, their limited field of view will intercept a small fraction of the incoming electron and proton fluxes. Such local measurements may either over or underestimate the realistic fluxes and dose rates.
The Directional Detector (DD) will allow for proper folding of the measured energy spectrum with the flux angular distribution, giving more accurate values of the averaged fluxes and dose rates. In addition, the comparison with the data from the MS and the redundancy of collected data will allow for the validation and verification of the performances of the detectors, as well as for better calibration. It will also provide better understanding of background and its processing for optimal retrieving of the clean data. The measurement of the electrons directionality along the JUICE trajectory is expected to give crucial and decisively important information for the analysis of the Jovian magnetosphere, inter-ference mechanisms with the moons magnetospheres and plasma diffusion mechanisms. The DD is specifically tailored to cope with very high fluxes of electrons with energies above 300keV. Its data, combined with the precise spectral measurement of the RADEM MS, will be valuable for the crosscorrelation with the measurements of the Particle Package: the plasma analyser for electrons from 1eV to 20keV and the particle analyser for 15keV to 1MeV. The DD is a valuable asset for the scientific data analysis and understanding of the complex Jovian Radiation Environment.

The objective of the proposed program is to develop the Directional Detector concept and to study its performance, while integrated in the RADEM instrument, for the duration of the JUICE mission. The different radiation environment models that exist for the Jovian system will be used to study the response of RADEM under the radiation environment expected at the different locations of the JUICE mission orbit and under different spaceweather conditions.

An extremely large number of studies rely on the Hydrogen Lyman-α (Lyα) emission line to survey, study and understand the distant Universe (z>2-3), as it is often the only feature available to spectroscopically confirm/study such galaxies. However, the escape fraction of Lyα (fescape) is highly uncertain at z>2, and much is unknown about what Lyα actually traces. How much are we missing by relying on it? How biased is our current view of the very high redshift, almost completely based on Lyα? Can we finally calibrate and understand Lyα and Lyα emitters?

In order to answer such questions, the student will conduct and work on very large (~5-10 deg2 surveys at z~2-3 (the likely peak of the star-formation history). This includes a perfectly matched) Lyα-Hα survey at z=2.23 using custom-made narrow-band filters specifically designed for this project (the first has already been delivered to the INT; PI: D. Sobral). By measuring Lyα/Hα ratios for a sample of hundreds of galaxies at z=2.23, the student will robustly measure fescape and the Lyα/Hα ratio as a function of mass, colour, environment and SFR and empirically calibrate Lyα for the first time, with very important applications/consequences for z>2 studies. The student will also lead the follow-up (using e.g. X-shooter and VIMOS on the VLT – some data already being taken) of many of the sources, resulting in the addition of accurate metallicity and dust extinction measurements (from a wealth of emission-line ratios). This will be a significant contribution towards unveiling the nature of Lyα emitters with a large, representative sample.

Furthermore, by conducting by far the largest survey (>2-4 orders of magnitude larger in volume than any other) for the most luminous Lyα emitters at z~2-3, the student will also detect >3000 powerful Lyα emitters and >100 Lyα “blobs” (the largest ~contiguous objects found in the Universe, many times the size of a single galaxy), determine their Luminosity Function for the first time and measure their correlation function and evolution. This will provide the first robust sample that can be directly compared with the highest redshift samples, to directly test whether there is evolution in the bright end of the Lyα luminosity function. This project will allow the student to observe on large telescopes to obtain the data directly (~20-40 nights over the first years), but also to do follow-up studies with e.g. VLT or ALMA to unveil and detail the nature of misterious Lyα emitters and blobs.

The Large Hadron Collider, at CERN, is the most powerful proton-proton collider ever built. When
it will re-start operation in 2015, it will collide protons with a center of mass energy of 13 TeV,
at a rate of 40 Million times per second, with a data-flow of the order of 1 PB/s. Out of all these
collisions, only a very small fraction is indeed interesting for physics analysis. The Trigger and
Data Acquisition system of ATLAS has the main role of selecting and storing about 400 interactions per
second for further analysis, using a combination of hardware and software based filtering systems.

The LHC will be further upgraded in 2018 to be able to deliver an even higher rate of collisions,
bringing an increase in data quantity of an order of magnitude or more. To find interesting physics
embedded in a huge amount of data, complex algorithms involving lots of computation are needed.
Several algorithms applied to LHC data are, already today, quite heavy on computations. In order
to keep the performance of the trigger system, to effectively select the relevant physics process while rejecting the backgrounds at the required rate, parallelization of the algorithms that are mining the data coming from the LHC detectors will be mandatory.

In recent years, several pervasive and affordable platforms capable of accelerating algorithms
through parallelization have appeared. The most notable are the FPGA (Field-Programmable Gate
Array), a pure hardware reconfigurable platform, and the GPU (Graphical Processing Unit) a
visualization-targeted specialized massively parallel processing device found at the heart of modern
PC graphical boards. For raw computing tasks, such as are the execution of Trigger algorithms, the
GPUs are far better suited than FPGAs. Modern GPUs perform calculations in double format (64
bits); implementing similar arithmetic units in FPGAs is very resource and time-consuming, what
favors GPU implementation.

This proposal is focused in the acceleration of algorithms used at the trigger level of the ATLAS experiment at the LHC (CERN) by parallelization of repetitive tasks and the use of hardware accelerators such as Graphical Processing Units (GPU).
Several groups at CERN and elsewhere are already studying GPU-acceleration of several algorithms -- Z finder, Kalman filter, integration of particle trajectories in detectors. This is an important area of work, especially when seen in the light of the increase in data flow, of around one order of magnitude, expected for the upgrade of the LHC.

This project will contribute to the development of the ATLAS Upgrade trigger algorithms and, as such, will be integrated in the Software Upgrade program of the ATLAS experiment.

The proposed research program aims at exploring gravitational physics in asymptotically AdS spaces and its relation to strongly coupled field theories. AdS gravitational physics has been extensively explored in the past years, starting from the most studied example of the AdS/CFT duality that relates N=4 SYM to type IIB strings in a ten dimensional space-time AdS_5 x S^5. This duality opened a new road for explorations that aim at constructing the QCD string, providing an entirely new language to describe the strong interaction. More recently, a more phenomenological approach considers simply gravitational physics in AdS with additional matter fields, instead of a full string theory, to describe the thermodynamics of putative strongly coupled field theories. Such framework can describe very non trivial IR physics that has many resemblances with condensed matter systems such as superconductors, fermi liquids and new exotic phases of matter. From the AdS perspective one considers the thermodynamics of black holes, particularly its phase diagram and critical exponents. More recently, new attention is being paid to quenches and the corresponding thermalization process. For instance, recently islands of stability have been found in AdS gravity subject to time dependent collapsing matter. These deformations almost lead to the formation of black holes, but then the system fails to collapse and nearly returns to its initial form. Such behaviour has also been observed in Conformal Field Theories subject to quantum quenches (a phenomena known as revivals).
The proposed work will aim at constructing new AdS black hole solutions, that result from introducing AdS boundary conditions that are dual to deforming the dual field theory with relevant operators, therefore drastically changing the IR physics. We will also explore time-dependent deformations, which describe quenches, and then study the gravitational evolution of the system.

The proposed work will be fully integrated within the international scientific community in the research area of the gauge/gravity duality, particularly through the participation in the ESF research network HoloGrav; the Marie Curie IRSES network UNIFY, the Marie Curie ITN network GATIS and the COST network “The String Theory Universe”.

Given the recent claim of the detection of primordial gravitational waves generated during inflation, it has become a pressing issue to examine whether these gravitational radiation does show unequivocal imprints of the gravity theory it has been originated by.

The aim of this work is to consider alternative gravity theories and analyse the generated gravitational waves they give origin to during inflation.

Motivated by the striking fact that 83% of the mass in the Universe remains a mystery, the so-called Dark Matter, our team joined the XENON collaboration for Dark Matter direct detection in 2004.

XENON (xenon.astro.columbia.edu) has consistently led the way for the discovery of Dark Matter, since the publication of its first results in 2007.
The phased program started with XENON10 (2005-2007) followed by the XENON100 detector that keeps on taking data since 2008, allowing as well for its detailed study and understanding of the physics processes involved in its operation.

Besides the outstanding record of 6 years of non-stop stable operation of a liquid xenon time projection chamber, XENON100 has also served as a test-bench for the next step in the program, XENON1T.

Being the only ton-scale detector financed and being built in the world, XENON1T is paving the way for the future of Dark Matter direct detection. It is due to start taking data in 2015 and will reach the dark matter sensitivity limit after 2 years of operation.

The candidate will contribute to the operational maintenance of XENON1T at the Gran Sasso NationaL Laboratory in Italy, including short stays of a few weeks at a time at the experiment location as well as in other partner institutions such as Columbia, NYU, etc.

The core work plan will be the development of analysis tools for XENON1T capitalizing on the extensive experience gained with XENON100. Other tasks will include remote monitoring of the vital parameters of the experiment as well as other remote tasks that can be performed away from Gran Sasso.

The successful candidate will have here an excellent of opportunity of integrating the highly stimulating environment of a world class experiment.

Context:
The first observations of geo-neutrinos, i.e. anti-neutrinos produced by natural radioactivity in the planet's crust and mantle, are recent but are already being used to test Earth models; anti-neutrinos produced in nuclear reactors have been classically used in neutrino physics, namely for the study of neutrino oscillations. The separation between those two signals is usually based on energy alone, and we plan to increase it by using also directional information for the first time.

The Sudbury Neutrino Observatory (SNO) is a large volume neutrino detector located in the SNOLAB underground laboratory in Canada. SNO has demonstrated that solar neutrinos do change flavour and thus have a small, but non-zero, mass. The SNO+ experiment will replace SNO's heavy
water target by liquid scintillator, that will provide sensitivity to several new low energy neutrino physics measurements, and in particular anti-neutrinos.

The detector upgrade of the SNO+ experiment (including the scintillator purification system, and calibration systems) is currently being completed and data taking is expected to start soon. The LIP group is responsible for several aspects of the calibration system – PMT and scintillator optical calibration, source insertion mechanism – as well as for the anti-neutrino analysis.

Project goals:
The expected rates of anti-neutrinos are small, but they can be clearly identified by the coincidence of a positron annihilation followed by a neutron capture, even with the background from the Tellurium decays. The positron energy and the neutron initial direction follow the anti-neutrino kinematics, and we aim to use the difference between the positions of the positron and neutron signals to help in the separation of the fluxes of reactor and geo-neutrinos, which come preferably from different directions. The final goal is the interpretation of the measured fluxes and spectra in terms of neutrino mixing and geological models.

The proposed work plan will involve all aspects of the anti-neutrino data analysis, from the development of selection algorithms for neutron identification and coincidence techniques, useful to identify anti-neutrinos (but also for the identification of background events), to the final signal measurement and interpretation.
The work will include also participation in in-situ activities in SNOLAB, including in the early stages the commissioning of the calibration systems, and later on, data-taking and calibration data analysis.

Young OB-type stars are among the most enigmatic objects in Galactic astrophysics; theories have elucidated the classical challenges in the physics of their formation. The scientific objective of this observational project will be to understand the variability properties of such objects to model the a) nature of accretion events, and b) constrain the masses and radii of the embryo's of high mass stars. The proposed thesis work will explore the asteroseismic properties of a) optically bright O stars deeply embedded inside some of the youngest HII regions in the sky, and b) a small sample of bright near-infrared counterparts of high mass protostellar objects. The thesis work will be based on working with data using very stable high resolution spectrographs and also priority data from the VISTA VVV to examine the light curves of infrared counterparts of high mass protostellar objects. A prospective student will have a strong foundation in undergraduate level physics and an exposure to methods in observational astronomy. A knowledge of programming in python, IDL and usage of astronomy data reduction softwares will be considered advantageous.

The late-time cosmic accelerated expansion is one of the most important and challenging current problems in cosmology. Although the standard model of cosmology has favored the dark energy models as fundamental candidates responsible for the cosmic expansion, the latter may be due to modifications of General Relativity, which introduce new degrees of freedom to the gravitational sector itself. This research project will explore the viability of a plethora of modified gravity models, consistently analyzing the reproduction of all the cosmological epochs. More specifically, we will consider generalizations of the Einstein-Hilbert action by including "quadratic Lagrangians", involving second order curvature invariants, such as Lagrangians involving non-linear curvature invariants, such as, f(R ) Lagrangians and modified Gauss-Bonnet f(G) theory (and modified versions of the latter), or Lagrangians which in addition to higher-order curvature terms also include couplings to the matter sector. Another class of theories under our scrutiny will be generalized scalar-tensor or vector-tensor gravity theories, where scalar or vector fields play gravitational roles that can also be perceived as couplings to matter in an appropriate frame. Additionally, another fundamental goal is to study the theoretical issues of the extra degrees of freedom of the theory and finally astrophysical applications in all of these classes of modified
gravity will also be analyzed.
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This project aims at obtaining a completely self-consistent set of very large-area Lyman-alpha surveys in 9 different redshifts/cosmic time slices from z=2.23, (2.8 billion years after the Big Bang) to beyond the current record distance z=9 (~500 million years after the Big Bang), each populated by up to >1000s of Lyman-alpha emitters (for z<6).

These surveys will be the largest, multi-cosmic epoch, narrow-band surveys, all undertaken in the same way (same reduction, selection). Because we already have pilot data (INT, CFHT, Subaru), the student's first results will be out way before e.g. Hyper Suprime-cam results. The samples (z=2.2, 2.4, 3.1, 4.3, 4.8, 5.7, 6.6, 7.1, 8.8) will include both AGN and star-forming galaxies, and also result in the largest samples of Lyman-alpha blobs (c.f. Matsuda et al. 2004) and of more typical LAEs.

One of the main goals is to find and confirm the most distant luminous galaxies (z=7.1 and z=8.8 surveys, where the number of sources will be low). With very large samples, spanning a range of luminosities and physical properties, and over different large areas on the sky, we will conduct the best clustering measurements ever done (across cosmic time), and look for signatures of re-ionization, e.g. significant change in the clustering of Lyman-α emitters; this will be a major improvement over e.g. Ouchi et al. (2010).

The high redshift Lyman-alpha surveys will be extremely large, >10,000 times larger than the typical ultra-deep fields, such as the HUDF with the NASA/ESA Hubble Space Telescope (e.g. Bouwens et al. 2011; Ellis et al. 2013), >20 times larger than e.g. Ouchi et al. (2008, 2010) and even larger (and significantly deeper) than e.g. Matthee, Sobral et al. (2014). The student will therefore derive by far the largest samples of the most distant galaxies and conduct detailed follow-up observations on the most luminous sources for the first time to unveil their nature and evolution (with e.g. MUSE/VLT).

There are several good motivations to extend the scalar sector of the Standard Model (SM). Models with an extended scalar sector usually have new sources of CP violation. It is already established that the SM cannot account for the observed baryon asymmetry of the Universe requiring new sources of CP violation. Furthermore some of these extensions
may also provide good dark matter candidates.

In addition, the existence of a richer scalar sector has important implications for flavour physics.

The directions of research pursued in this thesis work will depend on specific interests of the student and recent experimental and theoretical
developments in this field.

Black holes are the elementary particles of gravity,
and play a crucial role in fundamental physics, astrophysics, high energy physics and particle physics.

In the last years, our ability to understand strongly nonlinear phenomena involving black holes has opened up a new Golden Age in the field. General Relativity's 100 years are being celebrated with many new developments, ranging from Cosmic Censorship tests in violent scenarios to constraints on particle physics with supermassive black holes.

This project aims at understanding in full detail the relevance of black hole superradiance to constrain the masses of fundamental bosonic fields

Anti-neutrino interactions in liquid scintillator detectors like SNO+ can be clearly identified by the delayed coincidence of a positron annihilation followed by a neutron capture, in which the positron energy and the neutron initial direction follow the anti-neutrino kinematics. The difference between the positions of the positron and neutron signals can thus give an indication of the anti-neutrino direction. However, the sensitivity of this measurement is strongly dependent on the liquid scintillator characteristics, and must be calibrated directly on data. This work plan is devoted to the design, construction, testing and usage of a new directional Am-Be neutron source for SNO+.

In fact, the determination of the neutron direction can be an important tool in the anti-neutrino analyses, namely in the separation of sources from different directions. The more general objective is thus the understanding of the possible accuracy of such a measurement under different experimental conditions, and its impact for the separation between geo-neutrinos and neutrinos from reactors close to SNO+. A deeper understanding of the factors that, together with the calibration, determine the possible accuracy of this measurement, will be an important guideline for the design of future experiments and the corresponding calibration methods.

This thesis work should then have a reasonable component related to anti-neutrino physics but its main component will be in neutron propagation physics analysis and simulation and hardware work. Other possible application of such a neutron directional calibration source can also be considered within this framework.

Framework:
The first observations of geo-neutrinos, i.e. anti-neutrinos produced by natural radioactivity in the planet's crust and mantle, are recent but are already being used to test Earth models; anti-neutrinos produced in nuclear reactors have been classically used in neutrino physics, namely for the study of neutrino oscillations. The separation between those two signals is usually based on energy alone, and we plan to increase it by using also directional information for the first time.

The Sudbury Neutrino Observatory (SNO) is a large volume neutrino detector located in the SNOLAB underground laboratory in Canada. SNO has demonstrated that solar neutrinos do change flavor and thus have a small, but non-zero, mass. The SNO+ experiment will replace SNO's heavy water target by liquid scintillator, that will provide sensitivity to several new low energy neutrino physics measurements, and in particular anti-neutrinos.

The detector upgrade of the SNO+ experiment (including the scintillator purification system, and calibration systems) is currently being completed and data taking is expected to start soon. The LIP group is responsible for several aspects of the calibration system – PMT and scintillator optical calibration, source insertion mechanism – as well as for the anti-neutrino analysis. This project is focused on specific calibrations for the anti-neutrino directional analysis.

Tasks:
The design will involve the evaluation of existing isotropic Am-Be sources and the material selection to optimize the neutron shielding in all but the desired direction, and will rely on detailed simulations. The optimization of the source characteristics – neutron flux, spectrum and collimation – will take into account the full neutron calibration program of SNO+, to be prepared in parallel.

Before the construction of the final radioactive source, a prototype with the chosen materials and adequate geometry will be experimentally tested in realistic conditions using other neutron sources available at the Nuclear Technology Campus, in Sacavém. The final source will require also tests of material compatibility with the liquid scintillator, to be performed with other SNO+ collaborators.

The in-situ commissioning and usage of the source at SNOLAB will be the next step of the work. It will include the participation in data-taking and analysis of the calibration data obtained with the new directional neutron source, and the estimate of the impact on the final accuracy in the maps used for the separation of the geo and reactor anti-neutrino fluxes.

Finally, the usage of such a calibration source in future low energy neutrino experiments or for other applications will also be addressed.

The Pierre Auger Observatory aims at identifying the primary composition of cosmic rays and the sources which accelerate them to energies well above the ones achieved at Earth; but also at studying particle physics. At these energies, cosmic rays are not detected directly; the atmosphere acts as a calorimeter and an extensive air shower is produced.

The nature and sources of the UHECR have remained in mystery for decades. We still do not know their composition, and the acceleration astrophysical scenarios point to the most violent phenomena in nature, like Active Galactic Nuclei or Gamma Ray Bursts. Nevertheless, within the distances imposed by the interactions of UHECR with the Microwave Background, the amount of possibilities are constrained. The mass composition of the primaries, the energy spectrum and the arrival direction are key to unveil the UHECR secrets.

The Observatory is using 1600 water Cerenkov detectors covering an area of 3600 km2 to sample the shower particles when they reach ground. Those detectors measure the energy deposited by charged particles when releasing Cerenkov light in water. In addition to that, an optical telescope picking up ultraviolet light -which is produced by fluorescence of the nitrogen molecules excited by the cascade particles can actually see the longitudinal development of the shower whereas it crosses the atmosphere. Cerenkov light accompanies this emission carrying also valuable information.

The light profile imaged by the FD reflects the superposition of gamma showers from neutral pion decay; the time and position of muon detection in the SD gives direct indication of the profile of the decays of charged pions and thus they can open new windows to peer into the secrets of the hadronic interactions in showers, at energies above the ones tested at the LHC.

The observatory is also to deploy a series of complementary detectors that include: antennas for radio detection, a second detector acompanying all Cerenkov tanks (yet to be decided the specifics, the so called B2015), a set of buried scintillators (AMIGA), and an engeneering of segmented RPCs beneath the Cerenkov tanks (MARTA engeneering array).

The student is expected to identify new ways to extract information from the air showers and relate it to the high energy particle physics actual puzzles, and devise new techniques to measure these information, establishing experimental requirements, and possibly establishing their feasibility. Namely, the muonic information will be specially pursued.

Great amounts of enthusiasm and innovative thinking will be very helpful to achieve this goal. The student will be fully involved in the Auger Observatory, which is becoming the main test-bead for UHECR experiments through its multiple enhancements projects.

Collective modes in neutron stars

Summary
The transport properties of stellar matter depend on the modes which can be excited in this medium, either by its own free constituents (electron or neutron scattering) or by escaping neutrinos.
Collective modes in neutron stars (NS) will be studied in order to calculate: a) under which conditions there could exist an instability driven by the onset of hyperons; b) how the strong magnetic fields existing inside magnetars may affect isospin and density waves in asymmetric nuclear matter, in particular, the crust-core transition density; c) the spin waves in nuclear matter which may be in part polarized due to the presence of the magnetic field; d) the low lying collective modes in slab-like clusters existing in the inner crust of NS.

Motivation:
Compact stars, such as neutron stars, strange stars or hybrid stars, are unique laboratories that allow us to probe the building blocks of matter and their interactions at regimes that terrestrial laboratories cannot explore. They are ideal “laboratories” to study matter under extreme conditions of temperature, density, magnetic field and spacetime curvature.

The study of anomalous X-ray pulsars and of soft gamma-ray repeaters has brought more and more evidence for the existence of magnetars, young neutron stars with extremely high magnetic fields which power their emission. Also, the accurate measurements of neutron stars with masses around two solar masses (PSR J1614-2230 and PSR J0348+0432) has set important constraints on the nuclear equation of state, ruling out some theoretical models.

Although the crust represents only a small fraction of a neutron star, its thermic and elastic properties are crucial for the physical interpretation of the astrophysical observations related to these objects: starquakes, X-ray bursts, glitches, cooling. It is thus an important issue to characterize the transport coefficients (heat conductivity, charge conductivity and viscosity) and elastic properties of clusterized matter, and how they depend on the different configurations that can be expected. For sub-saturation densities we expect that collective modes of the nuclear matter may influence in a drastic way the opacity of neutrinos formed during the supernova explosion. The presence of spin domains could give rise to coherent effects which would increase a lot the cross section of neutrinos with a typical energy of a few MeV.

Another issue where the calculation of collective modes could bring interesting information is related with the possible existence of an instability driven by the onset of hyperons. The early conclusions ruling out hyperons from the NS core seem to be refuted by recent relativistic and non-relativistic mean-field models showing that a repulsive Sigma−N interaction is able to reconcile the two solar mass measurement with strangeness population. Since presently the information on hyperon interaction in hadronic matter is very scarce, different scenarios may be put forward depending on the choice of the hyperon couplings. In particular, it has been shown within a thermodynamical approach that a correct choice of the hyperon couplings could lead to the existence of instabilities inside a neutron star driven by the onset of strangeness, and still describe a 2 solar mass star. This could have important effects because in the vicinity of critical points the neutrino mean-free path is dramatically reduced so that a cooling slow down could be anticipated.

Objectives
The main objectives of the present project are:
1- imposing the few existing constraints on the hyperon interaction in hadronic matter, determine under which conditions collective modes in stellar matter due to density fluctuations will become unstable.
2- determine the density, isospin and spin collective modes in npe matter in the presence of a strong magnetic field. Determine the effect of the magnetic field on the crust-core transition by calculating the dynamical spinodal characterized by the surface where the frequency of the collective mode goes to zero.
3- calculate the low-lying modes for slab like-clusters in a Wigner-Seitz lattice.

Method
All calculations will be carried out within relativistic nuclear models. Collective modes will be determined within a relativistic Vlasov approach for stellar matter with neutron, protons and electrons (npe) only or including also hyperons (nphe). The realistic parametrizations that satisfy most of the laboratory constraints presently accepted will be used. Particular attention will be paid to the possible role of the density dependence of the symmetry energy. For the description of hyperonic matter mesons with hidden strangeness (sigma* and phi) will also be included. For the vector mesons we will go beyond the usual SU(6)-symmetry, and the couplings to the sigma* will be chosen so that an instability with the onset of hyperons arises. The description of the effect of ultra-strong magnetic fields will take into account the anomalous magnetic moment of the nucleons and the Landau quantization of the charged particle energy levels. For the calculations of collective modes in slab-like clusters we will consider as the ground state clusters determined within the simplified coexisting method with a zero thickness surface.

References
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Confinement and exotic hadrons with Lattice QCD

Quantum Chromodynamics (QCD) is the theory of quarks and gluons, particles constituting most of the visible matter. QCD is non-perturbative and the only known approach to eventually solve QCD is computing the Path Integral with Monte-Carlo techniques, eg Lattice QCD [1-5. We simulate tiny parts of the Universe at the fm scale of lattices with up to 100^4 space-time points. The QCD theory of particles and fields, with non-commutative groups such as the SU(3) 'colour' group and the SU(6) 'flavour' group, is very beautiful, and discretizing in on a lattice makes it even more interesting [1-5].

However this is computationally very demanding, and Lattice QCD is a Computational Physics topic [6-8]. We utilize the most efficient computers we can find. In CFTP, IST, U. Lisboa, we have been developing codes in C++ and CUDA to run the Graphics Processing Units (GUPs); and we have several servers with state of the art GPUs, parly supported by NVIDIA grants [9-11]. Our Lattice QCD students become outstanding programmers, able to address the most difficult numerical problems a physicist may solve.

Our Lattice QCD group at CFTP collaborates with the Lattice QCD group of the University of Coimbra (O. Oliveira and P. J. Silva), in common research and sharing computational facilities. We also manage joint FCT and European Union (Horizon 2020) projects. Our collaboration is PtQCD,
http://nemea.ist.utl.pt/~ptqcd/

Many open problems remain to be solved in Lattice QCD, needing both new technical improvements and new theoretical concepts. At CFTP we are able presently to study many topics such as confinement and chiral symmetry at the large finite temperatures [12-15] of the early universe and of heavy ion collisions or bound states and resonances such with few quarks and gluons [16-19], the hadrons (mesons, baryons, hybrids, glueballs, tetraquarks, pentaquarks).

The study of these problems in Lattice QCD, developing new Lattice QCD techniques [20-22] or new effective models [23-25] for quarks and gluons inspired in Lattice QCD, constitute the plan of the Thesis.

References:

[1] Confinement of Quarks
K. G. Wilson
Phys.Rev. D10 (1974) 2445-2459

[2] The Renormalization group and the epsilon expansion
K.G. Wilson, J. B. Kogut
Phys.Rept. 12 (1974) 75-200

[3] Hamiltonian Formulation of Wilson's Lattice Gauge Theories
J. B. Kogut, Leonard Susskind
Phys.Rev. D11 (1975) 395-408

[4] Compact Gauge Fields and the Infrared Catastrophe
A. M. Polyakov
Phys.Lett. B59 (1975) 82-84

[5] Quark Confinement and Topology of Gauge Groups
A. M. Polyakov
Nucl.Phys. B120 (1977) 429-458

[6] Monte Carlo Study of Quantized SU(2) Gauge Theory
M. Creutz
Phys.Rev. D21 (1980) 2308-2315

[7] A Monte Carlo Study of SU(2) Yang-Mills Theory at Finite Temperature
L. D. McLerran, B. Svetitsky
Phys.Lett. B98 (1981) 195

[8] Quark Liberation at High Temperature: A Monte Carlo Study of SU(2) Gauge Theory
L. D. McLerran, B. Svetitsky
Phys.Rev. D24 (1981) 450

[9] SU(2) Lattice Gauge Theory Simulations on Fermi GPUs
N. Cardoso, P. Bicudo
J.Comput.Phys. 230 (2011) 3998-4010

[10] Generating SU(Nc) pure gauge lattice QCD configurations on GPUs with CUDA and OpenMP
N. Cardoso, P. Bicudo
Comput.Phys.Commun. 184 (2013) 509-518

[11] Landau Gauge Fixing on GPUs
N. Cardoso, P. J. Silva , P. Bicudo, O. Oliveira,
Comput.Phys.Commun. 184 (2013) 124-129

[12] Lattice QCD computation of the SU(3) String Tension critical curve
N. Cardoso, P. Bicudo
Phys.Rev. D85 (2012) 077501

[13] Running Gluon Mass from Landau Gauge Lattice QCD Propagator
O. Oliveira, P. Bicudo
J.Phys. G38 (2011) 045003

[14] Gluon screening mass at finite temperature from Landau gauge gluon propagator in lattice QCD
P.J. Silva, O. Oliveira , P. Bicudo, N. Cardoso, Phys.Rev. D89 (2014) 074503

[15] Inside the SU(3) quark-antiquark QCD flux tube: screening versus quantum widening
N. Cardoso, M. Cardoso, P. Bicudo
Phys.Rev. D88 (2013) 054504

[16] Study of the gluon-quark-antiquark static potential in SU(3) lattice QCD
P. Bicudo, M. Cardoso, O. Oliveira
Phys.Rev. D77 (2008) 091504

[17] First study of the three-gluon static potential in Lattice QCD
M. Cardoso, P. Bicudo
Phys.Rev. D78 (2008) 074508

[18] Colour Fields Computed in SU(3) Lattice QCD for the Static Tetraquark System
N. Cardoso, M. Cardoso, P. Bicudo
Phys.Rev. D84 (2011) 054508

[19]Variational study of the flux tube recombination in the two quarks and two quarks system in Lattice QCD
M. Cardoso, N. Cardoso, P. Bicudo
Phys.Rev. D86 (2012) 014503

[20] Effective Polyakov line action from strong lattice couplings to the deconfinement transition
J. Greensite, K. Langfeld
Published in Phys.Rev. D88 (2013) 074503

[21] Gauge cooling in complex Langevin for QCD with heavy quarks
E. Seiler, D. Sexty, I.-O. Stamatescu
Phys.Lett. B723 (2013) 213-216

[22] Simulating full QCD at nonzero density using the complex Langevin equation
D. Sexty
Published in Phys.Lett. B729 (2014) 108-111

[23] Decays of tetraquark resonances in a two-variable approximation to the triple flip-flop potential
P. Bicudo, M. Cardoso
Phys.Rev. D83 (2011) 094010

[24] Lattice QCD signal for a bottom-bottom tetraquark
P. Bicudo, M. Wagner
Phys.Rev. D87 (2013) 11, 114511

[25] Matrix model for deconfinement in a SU(Nc) gauge theory in 2+1 dimensions
P. Bicudo, R. D. Pisarski, E. Seel
Phys.Rev. D89 (2014) 085020

Cosmic strings arise naturally in many proposed theories of new physics beyond the standard model unifying the electroweak and strong interactions, as well as in many superstring inspired inflation models. In the latter case, fundamental superstrings produced in the very early universe may have stretched to macroscopic scales, in which case they are known as cosmic superstrings. If observed, these objects thus provide a unique window into the early universe and possibly string theory. The goal of this thesis will be to study the evolution and astrophysical consequences of these objects, in the context of ongoing and forthcoming observational searches.

Motivated by the striking fact that 83% of the mass in the Universe remains a mystery, the so-called Dark Matter, our team joined the XENON collaboration for Dark Matter direct detection in 2004.

XENON (xenon.astro.columbia.edu) has consistently led the way for the discovery of Dark Matter, since the publication of its first results in 2007.
The phased program started with XENON10 (2005-2007) followed by the XENON100 detector that keeps on taking data since 2008, allowing as well to thoroughly study and understand the detailed physics of its operation.

Besides the outstanding record of 6 years non-stop operation of a liquid xenon time projection chamber, XENON100 has also served as a test-bench for the next step in the program, XENON1T.

Being the only ton-scale detector financed and being built in the world, XENON1T is paving the way for the future of Dark Matter direct detection. It is due to start taking data in 2015 and will reach the ultimate dark matter sensitivity after 2 years of operation.

The candidate work will contribute to the operation of XENON1T at the Gran Sasso Underground Laboratory in Italy, including short stays of a few weeks at a time. The work plan will include participation in other remote tasks as well as in the R&D on advanced photo sensors taking place in Coimbra, towards the next phase starting in 2018, with the upgrade of XENON1T to an even larger detector, XENONnT.

Our group in Coimbra (Atomic and Nuclear Instrumentation Group) has a more than 4 decades long experience in the development of noble gas filled detectors, including photo sensing innovative solutions, being widely recognized as a world leader in the field. The successful candidate will also have an excellent opportunity of integrating the highly stimulating environment of a world class experiment.

Polarimetry in hard X- and soft gamma-ray astrophysics is still a quite unexplored domain due to the great deal of complexity that this kind of measurement requires. In fact no dedicated polarimeters have ever been launched into space. To date gamma-ray source emissions have been studied almost exclusively through spectral, timing variability analysis of the measured fluxes and by using imaging techniques based on coded mask cameras or telescopes equipped with high efficiency focal plane detectors. By measuring the polarization angle and degree of linear polarization of the detected emission, it is increased by two the number of observational parameters thereby allowing better discrimination between different models. Polarimetric observations can provide important information about geometries, magnetic fields, composition and emission mechanisms in a wide variety of gamma-ray sources such as: pulsars, solar flares, active galactic nuclei, galactic black holes or gamma-ray bursts [1].

LIP - Coimbra has been developing for more than a decade both CdZnTe polarimeter prototypes and mass model simulation code for space polarimetry [2, 3]. Our group has also joined the latest major X- and gamma-ray telescope mission proposals to ESA Cosmic Vision, like DUAL or XIPE, where the main instrument was optimized for polarization measurements [4, 5]. In response to ESA M4 Call for Missions that will be announced in the second half of August 2014, our group together with other european partners will submit to ESA the AstroMeV proposal (http://astromev.in2p3.fr/). AstroMeV is a square-meter class instrument composed of two main detectors: a gamma-ray tracker made of a stack of semiconductor detectors (Si and/or CdTe) and a calorimeter composed of an ensemble of position-sensitive scintillator modules. The mission should carry WPOL wide field camera, which aims to monitor the X-ray/gamma-ray sources and to measure their polarimetric properties. This camera will be used in space to alert the main instrument in case of transient events (gamma-ray bursts, black hole binaries state transition, supernovae, etc.) and to map the X-ray/gamma-ray polarized sources in our Galaxy, which has never been done up to now.

The selected PhD student will contribute to instrument development in the framework of AstroMeV collaboration through focusing system and CdZnTe focal plane prototype testing under polarized beams, through mass model simulation using GEANT4 (http://geant4.web.cern.ch/geant4/) and MEGAlib (http://www.mpe.mpg.de/MEGA/megalib.html) simulation tools [6, 7] and by INTEGRAL satellite polarized source’s observation data analysis. Instrument sensitivity optimization should result in a configuration allowing a minimum detectable polarization lower than 5% (3σ) for mCrab equivalent source and 10^6s observation time.

[1] F. Lei, A. J. Dean, and G. L. Hills, “Compton Polarimetry in Gamma-Ray Astronomy”, Space Sci. R., 82, p. 309, 1997.
[2] R. M. Curado da Silva, E. Caroli, J. B. Stephen and P. Siffert, “CIPHER, a polarimeter telescope concept for Hard X-ray Astronomy”, Exp. Astron., Vol. 15, nº1, pag. 45-65, 2003.
[3] R. M. Curado da Silva, et al., “Polarimetric performance of a Laue lens gamma-ray CdZnTe focal plane prototype”, J. Appl. Phys., 104, p. 084903, 2008.
[4] P. von Ballmoos et al., “A DUAL mission for nuclear astrophysics”, Nucl. Instr. and Meth. Section A, 623, pp 431-433, 2010.
[5] Paolo Soffitta, R. M. Curado da Silva et al., “XIPE: the X-ray Imaging Polarimetry Explorer”, Experimental Astronomy 2013, DOI: 10.1007/s10686-013-9344-3.
[6] S. Agostinelliae, J. Allisonas, K. Amako “Geant4 - a simulation toolkit”, Nucl. Instr. and Meth. A, 506, pp. 250-303, 2003.
[7] A. Zoglauer, R. Andritschke and F. Schopper, “MEGAlib – The Medium Energy Gamma-ray Astronomy Library”, New Astronomy Reviews 50 (2006) 629–632

The observational evidence for the existence of a non-baryonic, non-luminous and non-relativistic component of the universe, accounting for ~80% of its total mass, has been strengthened in recent years. However, the nature and origin of this dark matter are still unknown. One of the strongest candidates are Weakly Interacting Massive Particles (WIMPs), expected to be detectable by looking at nuclear recoils from their elastic scattering with nuclei.
2-phase (liquid/gas) xenon detectors are the leading technology in direct WIMP search, and are used by the two most sensitive experiments in the world -- XENON-100 an LUX. LUX performed a first scientific run in 2013 with the goal of demonstrating its sensitivity. Despite the short duration of this run (85 days), it was able to set the most stringent limits ever to the WIMP-nucleon interaction.
The LIP-Coimbra team joined the LUX collaboration in 2010, after working in the ZEPLIN detectors since 2005. We are also part of the LZ collaboration, formed by merging the ZEPLIN and LUX teams, which proposes to build a new xenon detector with a mass of 7 tonnes with a sensitivity more than 1000 times better than todays best. The LZ project was recently selected as one of only two WIMP search experiments to receive support from the United States government for construction of the detector and science operations.
In this PhD project, the student will be integrated in an international collaboration and work in state-of-the-art detectors. He/she will be supported by a team with a large experience in all aspects of this type of experiment - namely, and more relevant for this work, in data acquisition systems, pulse and event analysis, development of high-level analysis filters and Monte Carlo simulation.
While most of the tasks will be performed in the LIP-Coimbra facilities, the year long second science run of LUX will occur during this project, so the student is expected to work on site, in the Sanford Laboratory (USA), for periods of up to 1 month, during the calibration of the detector and also during the acquisition of WIMP search data.

A high precision proton spectrometer (PPS) is under development by the CMS experiment. It uses a timing detector, the quartz timing counter (QUARTIC), coupled with silicon photomultipliers (SiPM), in order to measure the time of flight (ToF) of the two forward protons produced in the interaction point in the CMS detector. Considering central exclusive production processes (pp→pXp), 10 ps time resolution detector would provide 2.1 mm spatial resolution on the vertex position and improve of a factor of about 25 the background pile up suppression.

The subject of the thesis is the development of this detector, with focus on the readout system. In particular, a starting point will be the 64 channels 130 nm Tof photon emission tomography (TOFPET) chip developed by the LIP, intended for SiPM's signals readout and capable of 25 ps resolution. The resolution will be improved, as well as the digital interface will be modified to match the CMS trigger requirements.

One important reaction to be studied is gg→WW to measure the quartic gauge coupling WWgg. With 300 fb-1 integrated luminosity, the PPS expected sensitivities for the couplings a0W/Λ2 and aCW/Λ2 are of the order of 1 and 3x10-6 GeV-2 respectively (95% CL). These values are two orders of magnitude better than what is expected with the central detectors only for the same luminosity and 10^(3-4) times better than LEP and Tevatron. A number of other physics studies will be possible aiming at an understanding of the QCD mechanisms involved in exclusive central production.

There are a broad range of striking evidences from both astrophysical and cosmological observations that ~80% of the matter in the Universe is made of an unknown form which does not emit or absorb light - the so called Dark Matter (DM). The nature of DM is one of the most important and interesting open scientific questions, capable of attracting broad attention from the public. Moreover, the detection of DM would have a significant impact both on the observational astrophysics and cosmology and fundamental interactions.

The answer to the nature of the DM may lie in a generic class of Weakly Interacting Massive Particles (WIMPs). WIMPs, distributed in a halo surrounding our galaxy, would scatter off ordinary baryonic matter in terrestrial detectors. Various experiments are searching for these interactions using different techniques, but so far no clear evidence of a WIMP signals was found. Two of the best limits currently published in the literature (XENON100 and LUX) were obtained with dual-phase (liquid/gas) xenon Time Projection Chambers (TPCs), a technology that was first proven by the ZEPLIN-II experiment.

The LIP-Coimbra team joined the LUX collaboration in December 2010, after having worked in the ZEPLIN-II and ZEPLIN-III collaborations since 2005. LIP-Coimbra is also part of the LZ collaboration which is now proposing to design and construct a 7-ton liquid xenon DM TPC. With a fiducial mass of more than 5 tons, the experiment will probe WIMP-nucleon cross sections about 5,000 times better than current results.

The PhD student will be integrated in the LIP-Coimbra team which have an accumulated successful experience in the design and management of the Slow Control for DM experiences and also in the design and implementation of both pulse finding and position reconstruction algorithms. The proposed work will be carried out during the LUX 1-year long data taking run and while the LZ project will start to be build.

The outline of the main objectives for the PhD student is:

• Development of advanced pulse finding algorithms to parameterize the different types of signals acquired in a double-phase (liquid/gas) xenon time projection chamber. The algorithms should be robust and modular to allow its extension to other type of detectors and fields of expertise (e.g. nuclear security and medical imaging);

• Development of position reconstruction algorithms and study of their performance. The reconstruction algorithms will use the pulse parameters obtained by the pulse finder but should be generic and modular enough to allow its extension to other type of detectors and fields of expertise (e.g. nuclear security and medical imaging);

• Development of heuristic filters to analyze and detect different types of spurious events in the Slow Control (e.g. temperature and pressure extrusions, etc) which may lead to the deterioration of the detector performance and compromise the efficiency of the pulse finding algorithms.

The Pierre Auger Observatory, presently the world's largest cosmic-ray detector, detects the extensive air-showers (EAS) initiated by the interaction of ultra high energy cosmic rays (UHECR) in the Earth atmosphere at centre-of-mass energies up to 100 TeV, well above that of the LHC.

The Observatory, located in the Argentine Pampa, consists on a surface detector (SD) array of 1600 water Cherenkov tanks, sampling the shower secondary particles arriving at ground in an area of 3000 km² and a fluorescence telescopes detector (FD) imaging the longitudinal development of the electromagnetic component of the shower in the atmosphere.

The data collected so far allowed to establish important breakthrough results at the highest energies: the suppression of the flux and hints of anisotropy of the cosmic rays arrival directions. Also, several possible scenarios for the origin of the UHECR were ruled out, favouring astrophysical acceleration mechanisms.

Nevertheless, open questions remain to be solved, in particular about the origin and nature of the UHECRs. Currently, all under carried primary mass composition studies suggest either an unexpected astrophysical scenario or changes on the hadronic interaction physics at the highest energies. The answer to this puzzle implies a stronger knowledge about the shower physical mechanism, specially about the EAS muon content. This later quantity is directly related to the hadronic interactions that occur during the shower development and might help to break the current degeneracy of the shower observables between the primary mass composition and the hadronic interactions.

The Auger Collaboration is presently studying different options for the upgrade of the detector to improve the air-shower measurement.
In particular, the enhancement of the capabilities of the surface array for the identification of the muons produced in the EAS is a key aspect of the upgrade. In this context the LIP group is leading the MARTA project, proposing an innovative concept for the muon detection in Auger.
MARTA (Muon Auger RPC for the Tank Array) consists basically of robust RPCs (Resistive Plate Chambers) deployed under the tanks of the SD array, that will measure the muons on an event-by-event basis with high efficiency, and high timing and spatial accuracy.
These unique characteristics will further allow to measure simultaneously the muon signals in the tanks and in MARTA, providing a powerful tool to inter-calibrate both detectors and to monitor important parameters of the tanks.
Several full scale prototypes are already installed and taking data in the Auger Observatory: a muon telescope, consisting of two RPCs placed on the top and the bottom of one tank, has been operating for several months at the Observatory; two MARTA stations are being deployed in the field and starting to take data.

A MARTA Engineering Array (EA), consisting of about ten MARTA stations, will start to be deployed in the SD array during 2015.
The successful operation of the EA will be of the utmost importance for the proof-of-concept of MARTA.

The selected candidate will be involved in the activities of the LIP/Auger group, in particular those related with the instrumentation of MARTA detectors. The candidate will develop the readout of the RPC detectors and test them during the deployment of a MARTA Engineering Array. The candidate is also expected to take part in the detector installation and commissioning.
Each MARTA unit will consist of four RPCs, each with 64 pickup electrodes (pads). The signals coming from each pad must be amplified and recorded. The instrumentation system of MARTA must be able to record data from RPCs using a dual technique: Single Muon Counting using a simple threshold on each pad and Charge integration for high occupancy. The high number of acquisition channels implies that an ASIC should be used such as the MAROC chip, an identified candidate.
Furthermore the system must be able to cope with the stringent requirements of a Cosmic Ray ground array detector: It must be able to work in a remote location, with minimal maintenance, must have a low cost per unit, present a good timing for data synchronization (~10ns) and must be able to consume low power (few Watt).
The candidate will also work in cooperation with the Surface Detector Electronics group at Auger to discuss and implement the several interfaces and synchronization schemes.

The Pierre Auger Observatory aims at identifying the composition of primary cosmic rays and the sources which accelerate them to energies well above the ones achieved at Earth; but also at studying particle physics. In fact, at these energies, cosmic rays are not detected directly; the atmosphere acts as a calorimeter and an extensive air shower is produced by particle interactions at energies well above the LHC.

The Observatory consists on a surface detector (SD) array, sampling the particles arriving at ground in an area of 3000 km² in the Argentinean Pampa, and a fluorescence telescopes detector (FD) imaging the longitudinal development of the electromagnetic component of the shower in the atmosphere, leading to an almost direct measurement of its primary energy and the position of shower maximum, which carries important information on the first interactions and primary particle type.

The main advantage of the SD is that it has a 100% duty-cyle with contrast with a 10%-15% of the clear moonless nights in which the telescopes operate. However, its measurements are less direct and must be calibrated with hybrid events for which there are simultaneous measurements by the FD. The present ground stations are sensitive to both the electromagnetic and muonic components, but the Observatory plans to add an extra detector technology in order to improve the separation between both components.

In this project we concentrate on the measurement and analysis of the electromagnetic component at ground. The hybrid data set will be used to characterize the signals at ground, and their dependence on primary energy and shower development parameters, as well as the detector station response. The relation between the lateral and longitudinal electromagnetic shower shapes will be explored to search for new observables which can be used in the analysis of ground-only data.

One of our main goals is to extract an energy calibration independent of the muon content of the shower, decreasing the uncertainty due to its unaccounted fluctuations, and contributing to solve the “muon puzzle”. In fact, according to model predictions, extrapolated from much lower energy accelerator measurements, the present Auger SD results on muon content seem inconsistent with the results from the shower shape analyses in FD. Reconciling the muonic and electromagnetic shower components might be one of the best tests to particle interaction models at energies of 100 TeV.

Black holes are of great importance in studies in astrophysics, gravitation and fundamental physics.
One part of the thesis will involve purely classical investigations of black holes, in particular, black holes in strong magnetic fields and physics of particles and fields in their vicinity. Solutions of the Einstein-Maxwell are available by Ernst and other authors, which describe such configurations exactly. They are quite involved. However, in case of almost extremal black holes without external magnetic fields it is known that one can approximate the geometry around horizons by simpler metrics. One would like to see how such descriptions may be generalized for the cases when strong magnetic fields are present. Further points of interest involve other recent results like the presence of ergoregions far from rotating black holes in magnetic fields, as envisaged recently by Gibbons et al in 2013, or charged clouds of particles or fields which can be supported by just near-extremal Kerr-Newman black holes as discussed by Hod in 2014. Near extremal black holes are of utmost importance also from their thermodynamical and quantum properties. In addition, similar effects in case of weak but non-axisymmetric (not-aligned with hole's rotation axis) fields around black holes are of considerable interest.
Other parts of the thesis involve the black hole interior, the black hole horizon, and its relation to fundamental physics. For instance, one would like to find new regular interior black hole solutions and test their stability. In relation to the horizon one could combine both the Euclidean action and membrane paradigm approaches and obtain a direct derivation of the black hole entropy in the case there are electric and magnetic fields present. In the vicinity of the horizon one could also study important physical phenomena like generalized Banados-Silk-West effect, discovered in 2009, where black holes can act as particle accelerators with collisions, in principle, at arbitrarily high center-of-mass energies, or Meissner-type effects of the expulsion of the flux of axisymmetric magnetic fields from the horizons of extreme black holes which was demonstrated by Bicak et al some time ago and has been revived most recently. Finally, although black holes are objects not fully understood yet, from some of their generic properties one can extract important indications to a fundamental theory. Such a theory should include in a unified way, gravitation and quantum mechanics. We know from quantum calculations that black holes have a well defined entropy and temperature, the Bekenstein-Hawking entropy, proportional to the area of the black hole, and the Hawking temperature. Through several physical arguments one can deduce that the black hole entropy is the maximum entropy in a given region of space. This in turn led to the holographic principle as proposed by ’t Hooft and Susskind which states that, associating the entropy with the logarithm of the number of possible quantum states of the system, one is led to the conclusion that the fundamental degrees of freedom of a given region of space are in the area A of the region, and not in its volume, as one would expect a priori. Certainly, the fundamental theory has to take this into account. In this part of the thesis one wants to further develop the notion of black hole entropy, by studying instances and cases in which classical and quantum arguments mesh in the understanding of the fundamental degrees of freedom.

Modern physics is moving through very deep questions regarding the nature of the physical realm. Einstein´s theory of general relativity, opened the door for a dynamical role of space-time geometry in physics. We strongly believe there is a deep relation between the geometry of space-time and physical fields on a fundamental level. In general it is assumed that at some high energy scale there is a mathematical description that unifies different dynamical interactions. Historically, new ideas about space-time gave us new insights into physics by revealing new phenomena and/or improving our geometrical methods crucial for modern physics. In this context, extended theories of gravity have a great relevance. One possibility is to change the geometrical side of the gravitational field equations and include other geometrical entities previously unconsidered. In fact, the exploration of geometries beyond the (pseudo) Riemannian allows us to introduce torsion and search for its physical relevance in the construction of alternative theories of gravity and unified modern field theories.

This work will address a fundamental research on extended theories of gravity and its astrophysical and cosmological applications including gravitational waves. Some of the topics to cover, such as f(R) theories, gravity with torsion, the applications of these to cosmic acceleration and the dark matter problem, gravitational waves and also the coupling of gravity and electromagnetism, are areas of active research from the theoretical side that have became gradually more significant in observational astrophysics and cosmology. The possibility of testing these theories experimentally will be deeply explored. Also, the study of geons with extended theories of gravity has recently revealed to be a very rich domain of applicability of these theories in connection to the coupling of gravity and electromagnetism and astrophysical and cosmological issues such as blackhole remnants and primordial blackholes. Moving to the quantum domain, these geons might provide a deeper understanding of the relation between the local topological nature of the electromagnetic-gravitational (spacetime) vacuum and the quantum gravity challenge. This work will explore new horizons in the production of coupled gravitational-electromagnetic waves and their detection. These can have different sources since most astrophysical objects with a strong gravitational field also have a very strong electromagnetic field. We will study the perturbations of the gravitational-electromagnetic environment of geons and address several astrophysical and observational implications. All these open new windows for the physics of gravitational waves (in Einstein gravity and beyond) but also to the active research on the experimental tests of modified theories of gravity and spacetime torsion.

The European Extremely Large Telescope (E-ELT) is a ground-breaking project for a 39m diameter ground-based optical/NIR telescope with unprecedented scientific goals and system complexity. Portugal has recently joined as a member. Unlike current telescopes, the E-ELT is fully adaptive, since its optical elements adapt in real-time to changing observing conditions. The European Southern Observatory (ESO) leads and manages the overall E-ELT project development. Portugal is an ESO member for over a decade now.

Light propagating through the atmosphere is bent due to local variations of the index of refraction, the consequence of which are blurred images where the angular resolution – the power to distinguish light from 2 different sources apart – is severely damaged. Adaptive Optics systems use a set of wave-front sensors to measure the distorted wave-fronts, deformable mirrors to put it back to a planar shape and a real-time computer that estimates the wave-fronts from measurements. This is done both in a single direction (classical AO) or in the atmospheric volume (tomographic AO).

The wave-front reconstruction, name by which is known the inverse problem of estimating the wave-front from the measurements involves massive computation, in particular for E-ELT-sized AO systems.
Recent progress in real-time implementation of wave-front reconstructors for adaptive optics applications have shown the huge potential for spatial-frequency domain techniques – or commonly called Fourier-domain techniques – for they scale much slower than conventional vector-matrix multiplies used hitherto to solve linear systems of equations or the order 10k squared or so.

Of particular interest for wide-field and extreme adaptive optics alike, Fourier-domain reconstructors have been developed in the last decade and are now ripe for further testing and implementation. There are still some shortcomings mainly emanating from the incomplete forward model that neglects several error terms.
This project has three major components:
1) high-performance computing simulations with the analytical development of a novel approach to remove remaining errors after reconstruction
2) extend results to the pyramid wave-front sensor in tight collaboration with Italian partners
3) implementation and test on an Adaptive Optics optical bench at LAM – Laboratoire d'Astrophysique de Marseille.

Profile: Student with strong interest in astronomy, mathematical modelling, numerical simulations, data/signal processing, statistical methods, optics. Availability for extended missions in Marseille is required.

References
C. Correia et al, Anti-aliasing Wiener filtering for wave-front reconstruction in the spatial-frequency domain in adaptive-optics-assited astronomical high-contrast imaging instruments JOSA-A, submitted (Jul 2014)
C. Correia, C. Kulcsar, J-M. Conan and H.-F. Raynaud, Hartmann modelling in the Fourier domain; Application to real-time reconstruction in Adaptive Optics, Proceedings of the SPIE - Ground-based Astronomical Instrumentation, Volume 7015, 2008. http://dx.doi.org/10.1117/12.788455

Supervision: Carlos Correia and Thierry Fusco (LAM - Marseille)

In the COMPASS experiment collisions of polarised muons with polarised targets (6LiD, NH3) allow the study of the nucleon spin dependent structure functions. One of the main goals has been the extraction, via the Semi-Inclusive Deep Inelastic Scattering (SIDIS), of the contributions of the different quark flavours and of the gluon to the nucleon total spin. The COMPASS International Collaboration has about 220 members from 22 institutes.

In the framework of the next approved COMPASS programme, in which the LIP group has, together with the Torino group, the leadership, important studies are being addressed leading to the first world measurement of the polarised Drell-Yan (DY) process via its muon pair decay.
The COMPASS setup was redesigned in order to perform a dimuon experiment with the use of a high intensity pion beam of 190 GeV/c colliding with a NH3 polarised target for measuring transversely polarised DY. The data taking will start shortly, a pilot run in the fall of 2014 and a full year run in 2015.

The aim is the study of azimuthal asymmetries, which allow the extraction of correlations between the parton transverse momentum and the nucleon spin, from which some of the Transverse Momentum Dependent Parton Distribution Functions (TMD PDFs) will be extracted, namely Sivers, Boer-Mulders and pretzelosity functions.
Another goal is the comparison of these results with previous COMPASS ones coming from SIDIS. A first objective is to check the QCD prediction that some of these functions, although universal, change sign between SIDIS and DY.
Also addressed will be the study of Psi asymmetries in view of a polarisation measurement. These studies can also lead to a better understanding of Psi production mechanism, namely the duality between Psi and Drell-Yan productions.

While the number and variety of discovered extra-solar planets is still an important asset for
exoplanet research, the focus of extrasolar planet researchers is now moving towards two main
lines: i) the detection of lower and lower mass planets, with the goal of finding an Earth sibling, and
ii) the finest characterization of planets orbiting other stars, including their interior structures and
atmospheres.

Despite the development of a whole new generation of instruments and space missions (like ESOESPRESSO
and ESA’s CHEOPS and PLATO missions, on which our team is deeply involved),
these goals are not easy to achieve. In particular, the “noise” introduced by stellar magnetic activity has been
shown to be a strong source of difficulties for planet search and characterization programs using
both high precision radial velocity or photometric transit observations.

The present project proposes to investigate the impact and role of stellar activity in precise planet
search and characterization projects. For this, we expect the student to develop a numerical tool to simulate the physical
effects of stellar magnetic activity (spots, plages, granulation) on precise photometric (transit) and radial velocity measurements. The tool
will then be applied to real data (e.g. HARPS and Kepler). The impact of stellar activity on the
derivation of precise planet parameters will be investigated in detail. The results of this project have
crucial consequences for the full success of instruments like ESPRESSO, CHEOPS, and PLATO.

Euclid is an ESA medium-class mission, due to be launched in 2020, whose main goal is to understand the physical origin of the accelerated expansion of the universe. CAUP is an affiliated institute of the Euclid Consortium and is actively involved both in the technical preparation and in the scientific exploitation of the mission. This project will contribute to the latter. Its main goal will be to carry out a detailed assessment of Euclid as a precision tool for consistency tests of the LambdaCDM paradigm and for searches for new physics. Inter alia, some attention will be given to tests of the stability of fundamental couplings a special attention to the variation of fundamental constants, and we will explore possible synergies with ground-based spectrographs such as ESPRESSO and HIRES (a proposed CODEX-like spectrograph for the E-ELT). The work will be done in the context of the Euclid Science Working Groups.

The on-going Gaia-ESO Survey is a very ambitious project which uses ESO/VLT to obtain detailed spectra of about 100000 stars from all the Galactic stellar populations. We propose to use the data from this survey (for which we have privileged access) to study the chemical and kinematic properties of stellar populations. The goal is to understand the formation and evolution of the distinct populations that we can identify with the data. In addition, we propose to investigate the observed planet hosting stars to understand possible links between the different stellar populations and planet formation processes. This latter study should help us to better estimate the frequency of the different type of planets for each stellar population and in our Galaxy in general.

The Large Hadron Collider will collide proton and lead ion beams with a center of mass energy of 13 TeV and 5.13 TeV, respectively, after the current shutdown for Accelerator and Detectors upgrades. ATLAS is one of the
four detectors built at the LHC to look into the smallest constituents of matter. It was designed to search for the
Higgs boson of the Standard Model (SM) of Particle Physics and for new particles predicted by new physics
models beyond the SM. ATLAS participates also in the Heavy Ion Program of the LHC in order to study the Quark Gluon Plasma, a state of matter in which quarks and gluons are no longer confined under strong interaction.
The LHC collides beam particles with a very high frequency, 40 MHz, but only a very small fraction is indeed interesting for physics analyses. The Trigger and
Data Acquisition system of ATLAS has the main role to select and store about 400 interactions per second for
further analysis. In order to achieve this goal, the trigger system is divided in three levels. The first one is
hardware based, while the two following use dedicated software algorithms to confirm the selection done by the
first level trigger.
One important problem is the high rate of fake muons originating in the beam halos, or by accidental coincidence of hits of charged particles, like pions or kaons, in the muon spectrometer. These fake muons, in turn, produce high rate of fake heavy flavour jets (collimated sprays of particles) erroneously tagged as containing muons from B-meson decays. The outer layer of the Tile calorimeter can contribute significantly to eliminate these fake rates. In particular, the new read-out electronics of the calorimeter will improve significantly the signal to background ratio, enhancing the potential of rejecting fake muons in a wide window acceptance. The full integration of the new readout electronics is planned for the SLHC (after 2022), but a first prototype is planned to operate already in 2015. This prototype can be used to develop the heavy flavour jet trigger using the Tile calorimeter in both first and subsequent trigger levels.
The work will be developed mostly at LIP - Laboratório de Instrumentação e Física Experimental de Partículas. The student will explore the possibility of using the outer layer of the Tile calorimeter at trigger level, in order to improve the efficiency and purity for tagging Heavy Flavour Jets.
The student should have solid computing skills, namely in C++ programming, and must be available to travel to CERN for short periods (1, 2 weeks), several times in the year, for implementation tests.

Quantum Chromodynamics, the theory of the strong interactions, predicts that matter should exhibit two distinct phases - a hadronic phase at lower temperatures, where the degrees of freedom are composite bound states of quarks and gluons, and a partonic phase at extreme conditions of energy densities or temperatures. The latter corresponds to a deconfined system and it is thought to be equivalent to a plasma of quarks and gluons. Such a deconfined system would have occurred a few microseconds after the Big Bang, and it is expected to set in the core of the neutron stars.
Nucleus-nucleus collisions at the Large Hadron Collider (LHC) provide an excellent op- portunity to create the Quark Gluon Plasma (QGP) in the laboratory energy frontier. The ATLAS experiment provides essential capabilities to study it, namely large accep- tance, high granularity calorimeters, tracking detectors and muon spectrometers.
A major goal of the Heavy Ion Program of the LHC is the understanding of the effects of the QGP on heavy flavour jets (collimated sprays of particles originating on the hadro- nization of “bottom” quarks). The main motivation arises because the “bottom” quark constitutes an excellent probe to study the nature of the energy loss suffered by the quarks while travessing the QGP.
The ongoing upgrade of the ATLAS detector towards Run II (after the current LHC shut- down) enhances the capabilities of studying such observable.

This is an experimental PhD program and the work will be developed mostly at LIP - Laborato ́rio de Instrumenta ̧ca ̃o e F ́ısica Experimental de Part ́ıculas. The student will participate in data acquisition at CERN, either of p+p collisions at 13 TeV or Pb+Pb collisions at 5.13 TeV, and will analyse the data. This analysis involves the measurement of the transverse momentum spectra of both heavy flavour jets and the ones that result from the hadronization of “up”, “down” and “strange” quarks. For such measurements he(she) will need to develop algorithms in C++. Furthemore, he(she) will participate in the technical activities in which the ATLAS/LIP group is involved, namely in the Tile calorimeter and/or in Trigger system.

The student should have solid computing skills, namely in C++ programming, and must be available to travel to CERN for short periods (1, 2 weeks), several times in the year, in order to participate in the data acquisition and in the analysis’ group meetings, as well as technical activities related to detector operations.

The quark gluon plasma created in ultrarelativistic collisions of heavy ions offers unique opportunities to explore the dynamics of strongly coupled systems.

The possibility to experimentally measure at the LHC detailed properties of jets in the heavy ion environment has triggered growing interest in the development of theoretical techniques that can provide a bridge between observation of modifications of jet properties to specific characteristics of the quark gluon plasma.

This projects aims at providing detailed spatio-temporal images of the quark gluon plasma obtained from the properties of the jets that propagate within.

In this proposal it is intended to build and to study the implications of models of interaction between dark energy, dark matter and states of the Standard Model. Particular attention will be paid to the coupling to the neutrino and the Higgs sectors.

One of the greatest challenges facing observational cosmology is understanding the formation of large scale structure in the Universe. Hierarchical models for structure formation developed over the last few years, achieving the high degree of predictive success that they do, are however still unconstrained, in particular in helping to understand how the light (galaxies) traces the underlying (dark) matter and how this relation evolves over time. We will address this problem by performing a systematic study of the evolution of the densest regions of the Universe, as traced by the most massive galaxies and their environments, improving our understanding of how the most massive regions of the Universe form and evolve. This will only be possible by using data from a deep mid-infrared wide-field survey, the Spitzer Extragalactic Representative Volume Survey (SERVS), which has just finished the data processing for a 1400 hour-long observational programme capable of finally overcoming long-standing observational limitations.

In this thesis, the student will:
a) use the deep radio surveys of these fields, already performed either at 1.4 GHz (VLA) or 610 MHz (GMRT), or both;
b) identify High-redshift Radio Galaxies in these fields. This will be possible either by studying Ultra Steep (Radio) Spectrum sources, candidates for such objects (when radio observations exist at more than one frequency), or by directly estimating radio luminosities of radio sources using the existent spectroscopic or newly obtained accurate photometric redshifts. The wide area nature of SERVS, covering 18 deg2 of the sky (or 0.8 Gpc3 over 110^13 Msun) dark matter haloes will be contained in this volume. Many will have a massive galaxy in its core, and many of these should be very luminous at radio wavelengths;
c) identify companion galaxies to the radio galaxies, thus tracing the environments of the most massive galaxies. Identification of candidates will be performed on the basis of projected distance in the infrared data, and photometric or spectroscopic redshifts will then be used to confirm the physical connection to the Radio Galaxy. The sensitivity of SERVS is enough to detect galaxies with characteristic luminosity (L*) to z~5, which will allow a detailed census of the vicinity of the Radio Galaxy to be performed;
d) characterize the environments of these massive radio galaxies, by measuring density of companion galaxies, and their properties: obscured and unobscured star-formation and AGN activity, stellar masses, star-formation ages. This will provide a comprehensive characterization (current state and history) of the environments of massive Radio Galaxies, which will be tracing the most massive dark matter haloes. By using SERVS data we will be able to cover rest-frame near-IR emission from our selected galaxies, sampling light from both old stellar populations and younger AGB stars. Together with improved stellar population synthesis models, this will allow for a reliable determination of galaxy ages and masses, robust against degeneracies;
e) map the evolution of clustering properties in massive dark matter haloes over a significant fraction of the Universe’s history, and compare with predictions from hierarchical structure formation models. This will result in a fundamental test for such models, and will reveal how they should be improved to better explain the formation and evolution of large scale structure in the Universe.

Tests of the spacetime stability of nature’s fundamental couplings recently became an extremely active area of research, and are listed among ESA and ESO’s science drivers for the next generation of facilities. While a detection of variations will be direct evidence of Equivalence Principle violations and a fifth force in Nature, any such measurements (even null results) can provide tight constraints on additional dynamical degrees of freedom (such as fundamental scalar fields) that are known to be among Nature’s building blocks. The thesis will explore the role of these astrophysical tests on fundamental physics, with some emphasis on dynamical dark energy. Initially the work will be done in the context of a UVES Large Program (whose data analysis is ongoing), but forthcoming facilities such as ESPRESSO and ELT-HIRES will become more relevant as the thesis progresses.

The Standard Model of Particle Physics (SM) is a very successful theory that describes the fundamental constituents of matter and their interactions. It is, however, incomplete since there are many questions it cannot explain, like the origin of Dark Matter in the Universe or why matter dominates over anti-matter. One of the missing pieces of the SM that has not been fully probed by experiments up to now is the mechanism through which the fundamental particles acquire mass, so-called Higgs mechanism. In the SM, this happens through the interaction with a new particle, the Higgs boson.
The recent discovery of a Higgs boson at CERN by the ATLAS and CMS experiments was a very important milestone in this quest. The focus of both collaborations goes now into the precise measurement of all the properties of this new particle, to probe its nature, testing the SM predictions and searching for new physics if deviations from the expectations are found.

This project proposes a study of one of the possible production mechanisms of the Higgs boson in the LHC proton-proton collisions, the so-called Higgs-strahlung process, in which the Higgs is produced in association with a W boson, when the Higgs decays to b-quark pairs and the W boson to a lepton and a neutrino. The spin and CP quantum numbers of the Higgs leave their footprint in the angles of the decay products of the Higgs and the W boson. By combining the information of the different decay particles it will be possible to measure the Higgs boson spin and CP properties. Any deviations with respect to the SM expectations can be a sign of new physics.
This PhD project involves the analysis of the 13 TeV pp collisions that ATLAS will collect during the run II, starting in 2015. Analysis algorithms that use the standard ATLAS software tools will be developed to search for the Higgs decaying into b-quark pairs in the associated production channel and to study observables that are sensitive to its spin and CP properties. Comparisons with theoretical models, using Monte Carlo simulation, will be performed. In addition, the student will participate in the ATLAS data taking and physics analysis activities, with frequent trips to CERN to participate in shifts and in collaboration meetings.

The Standard Model of Particle Physics (SM) is a very successful theory that describes the fundamental constituents of matter and their interactions. One of the missing pieces of the SM that has only very recently started to be probed by experiments is the Electroweak Spontaneous Symmetry Breaking mechanism through which the fundamental particles acquire mass. This mechanism foresees the existence of a new particle, called the Higgs boson. The discovery of a new particle by the ATLAS and CMS experiments at CERN, in July 2012, followed by the first measurements of its properties showing that the new particle was compatible with being a Higgs boson, were important milestones in this quest. The focus of both collaborations, ATLAS and CMS, for the near future will be the precise measurements of the Higgs boson properties in order to test wether there is only one, as predicted by the SM, or more as predicted by beyond the SM theories (like the 2 Higgs Doublet Models or Super-Symmetry). Any significative difference of the measurements with respect to the SM predictions can be a sign of new physics.

A distinctive property of the Higgs boson is that it couples to fermions through the Yukawa coupling proportional to the fermion mass, so some of the most important measurements to be done now are the couplings to the different fermions. For the LHC run I, the sensitivity to the fermion couplings (either through the H->tau tau or H->bb decay channels or indirect constraints on the Higgs coupling to the top quark) was very limited. These measurements will be improved with the increased luminosity and higher center of mass energy expected for the run II at 13/14 TeV.
The decay channel with the highest branching ratio, H->bb, is at the same time one of the most difficult ones in a hadron collider, due to very large backgrounds, but essential to measure the Higgs to b-quark coupling. The associated production channel of a Higgs with a W boson provides, through the semileptonic decay of the W boson, a good way to reduce the background and therefore observe the Higgs decaying to b-quark pairs.

The goal of this project is to carry out an improved precision measurement, with the ATLAS/LHC Run II data, of the cross section times branching ratio for the channel where it is produced in association with a W boson, when the Higgs decays to a pair of b-quarks, an essential measurement to extract the coupling of the Higgs boson to the b-quark. The methods to reach that goal will include developing ways to deal with the increased pile-up due to the higher luminosity, and improving the Multi-Variate Analysis technique currently used.

This PhD project involves the analysis of the 13/14 TeV pp collisions that ATLAS will collect during the run II (2015-17). In addition, the student will participate in the ATLAS data taking, detector calibration and physics analysis activities, with frequent trips to CERN to participate in shifts and in collaboration meetings.

The top quark is the heaviest elementary particle discovered so far and the study of its properties provides not only an important test of the Standard Model (SM) of particle physics, but also a window to physics beyond it. At the run-1 of CERN's Large Hadron Collider (LHC), both the ATLAS and CMS collaborations developed an extensive programme devoted to the measurement of top quark properties. In fact, the LHC is a true top-factory with several million top quarks being produced every year. Top-quark physics is thus precision physics at the LHC and the top-quark will be studied like never before. It will certainly be the best place to indirectly look for physics beyond the SM.

With so many top-quarks being produced, a precise measurement of the top quark couplings will be performed at next LHC run. The expected luminosity and centre of mass energy, at the LHC run-2, will allow to further pursue top-quark studies, namely on the flavour changing neutral (FCN) couplings to the SM gauge bosons. In the SM the top quark decays via flavour changing neutral currents (FCNC) have extremely small branching ratios but some of its extensions, such as supersymmetry, technicolor or multi-Higgs doublet models predict a significant enhancement of the probability for such decays.

An important way of probing the FCN coupling tqZ (with q being a u or c- quark) is the search of tZ production via FCNC. A similar search would also allow to probe the tqg FCN coupling (where g is a gluon). Furthermore, the study of the tZ production in the context of the SM is an important measurement, providing relevant information to many other important results (as background), such as the measurement of the ttZ and ttH cross-sections.

The project has a theoretical component related to the interpretation of the results in the context of an effective theory. This effective theory will be presented in the form of a dimension six Lagrangian allowing to parametrize new physics that could be discovered at the LHC in a somehow model independent way.

The present proposal foresees the integration of the applicant in the Portuguese ATLAS group, profiting from the expertise of the group in multi-lepton topologies. An analysis strategy will have to be developed, considering the challenging pile-up conditions expected for the run-2 data. The evaluation of systematics uncertainties, testing new strategies to control them, and a close collaboration with the phenomenological community in the interpretation of the experimental results will be crucial to fully exploit the potential of the new LHC data.

The top quark is the heaviest elementary particle known, with a mass close to the electroweak symmetry breaking, and it can provide clues about the symmetry breaking and the Higgs mechanisms. It is thus an excellent object to test the standard Model of Particle Physics (SM). There is an important effort to study the top quark properties, like its mass, production cross-sections, electric charge, spin, decay asymmetries, rare decays, etc...

Deviations from SM predictions of the production and decay properties of the top quark provide model-independent tests for physics beyond the SM. According to the SM, the top quark decays nearly 100% of the time to a W boson and a b quark. The Cabbibo-Kobayashi-Maskawa (CKM) quark mixing matrix is related to the rates of the Flavour Changing Charged Current (FCCC) decay modes. Some of the elements were not yet directly measured but are determined from the unitarity conditions of the matrix. A direct measurement of these elements put strict conditions on the assumptions behind the matrix properties, as the existence of only three families on the SM.

This research program will be developed within the Portuguese ATLAS group. It aims to measure, with LHC data collected by the ATLAS detector, the decay rate of the top quark into a W boson plus a s-quark and thus, measure also the amplitude of the CKM element Vts, which its present estimated value is Vts = (42.9+-2.6)×10-3.

On July, CERN announced the discovery of a particle with Higgs-like properties, predicted in 1964 by Higgs, Englert e Brout, for which the first two received the 2013 Physics Nobel Prize. This particle corresponds to a spin-zero field, necessary to give mass to the remaining particles in the Standard Model of electroweak interactions. There is no fundamental argument determining the number of scalar particles. Thus, as one probes further into the properties of the particle discovered, one must look for the differences which will exist in case there are more than one scalar; the so-called Multi-Higgs models. In this project, we wish to explore the consequences for LHC and ILC of the presence of more than one Higgs field. Conversely, we wish to understand how current and upcoming data affects these models. The project will be co-supervised by João P. Silva and Jorge C. Romão and can have a larger interface with phenomenology or be more theoretical, depending on the interests and abilities of the student. A current MSc student working on similar topics had one published article and one submitted in less than one year.

Studies of the high redshift Universe have relied on a number of methods to identify increasingly distant and, consequently, younger galaxies. Radio selection has been reborn as one of the most promising methods, as powerful radio AGN can currently be detected at radio frequencies at essentially any redshift. Using the next generation of deep radio surveys, these searches are now being pushed to new sensitivity levels, to find radio AGN at the highest distances and at the earliest formation stages, presumably well within the Epoch of Reionization. Using multiwavelength data (x-rays, optical, infrared and millimetre, besides the radio itself), the faint radio population has started to be characterised, contributing not only to a better understanding of the radio sky, but, even more interestingly, selecting elusive, more extreme sources that can only be understood with the upcoming full capabilities of the Atacama Large Millimetre Array. These studies are exciting, but can only currently be performed over very small areas. Extending such studies to virtually the whole sky is a prime objective of the next generation of radio surveys, and this project aims to play a pivotal role in such expansion.

The host institution for this project is involved (with co-Is and co-PIs) in two of the most ambitious projects in the pre-Square Kilometre Array era, surveys that will map the entire sky at 1.4GHz at microJansky levels. The Evolutionary Map of the Universe (EMU), to be performed with the Australia Square Kilometre Array Path]inder, will cover the sky at declinations below 30deg, while the Westerbork Observations of the Deep APERTIF Northern-Sky (WODAN) will cover the northern regions. Both surveys should start producing data by 2015. Together, the EMU and WODAN surveys will produce a unique dataset that, together with other multiwavelength data being obtained or soon to be obtained, will be able to find the most extreme and unique radio galaxies, including the first-generation of powerful AGN in the Universe, in the Epoch of Reionization. This project proposes to (a) establish a set of objective criteria for the selection of very high redshift radio galaxies; (b) find and analyse candidates for very high redshift radio galaxies, including the preparation of follow-up observations of particularly interesting candidates with ALMA; (c) play an active role in the optimisation of the next generation of ultra-deep whole-sky radio surveys, the EMU and WODAN projects, in order to explore more efficiently the highest red-shift Universe.

The Sudbury Neutrino Observatory (SNO) is a large volume neutrino detector located in the SNOLAB underground laboratory in Canada. It consists of a 12 m diameter transparent acrylic vessel surrounded by 9500 very sensitive light detectors (photomultipliers, or PMTs). The large water volume around the acrylic vessel (several thousand tons) and the underground location (2 km depth), make it a very low-background facility, ideal for Neutrino Physics. SNO has demonstrated that solar neutrinos do change flavor and thus have a small, but non-zero, mass. The SNO+ experiment will replace SNO's heavy water target by liquid scintillator, that will provide sensitivity to several new low energy neutrino physics measurements.
If it exists, the rare process of neutrino-less double-beta decay would prove that neutrinos are Majorana particles – their own antiparticles – and would allow the measurement of the absolute scale of neutrino masses. SNO+ will use the advantages of a large mass and very-low background detector to search for this process by loading large quantities of Tellurium in the liquid scintillator.
During all the phases, SNO+ will also detect anti-neutrinos from nuclear reactors and from the Earth's natural radioactivity, as well as galactic Supernova neutrinos.
The detector upgrade of the SNO+ experiment (scintillator purification system, new acrylic vessel support, new calibration systems, etc..) is currently being completed at SNOLAB, in Canada. Data taking is expected to start in 2015. A short commissioning run period with pure liquid scintillator will be followed by the Tellurium-loaded phase. In later phases – with pure liquid scintillator again – SNO+ will also be able to measure several components of the solar neutrino spectrum. The LIP group is responsible for several aspects of the calibration system – PMT and scintillator optical calibration, source insertion mechanism – as well as Anti-neutrino analysis.

The broad scope project's goals are to obtain the first neutrinoless double-beta decay limits (or positive measurement) with SNO+. The quality of the measurement is crucially dependent on the detector's energy resolution, since the signal is a narrow energy peak, and on achieving the lowest possible backgrounds. The work plan for this thesis project will target the first of these aspects, by means of the energy calibration with different sources.
Being a homogenous unsegmented scintillation detector, the uniformity of the energy response of SNO+ depends crucially on an accurate knowledge of how the scintillation light is produced, propagated and detected. Several effects impact that knowledge, mainly the processes of absorption, re-emission and scattering of light, as well as refraction and reflection on the detector elements. Due to the large dimensions of the detector (diameter of 17 m), the in-situ measurement of these properties is essential, and makes use of several optical sources, from uniform diffusers to narrow beams of laser light.
The goals of the project are to obtain the full optical characterization of the SNO+ detector, in different detector configurations, namely the isotope loading. For that, the existing multi-parameter analysis methods, inherited from SNO, need to be adapted to liquid scintillator. This adaptation will need to take into account several differences between water and scintillator, from the point of view of optics:
- optimization of the used wavelengths, in order to cover the appropriate spectra, and to measure the effect of absorption/reemission with/without the use of wavelength shifter,
- optimization of the chosen source positions, in order to take into account the effect of total internal reflection at high angles of incidence in the acrylic sphere;
- developmente of a new optical fit algorithm that can use both direct and non-direct light in a simultaneous measurement of the absorption and scattering.
The validation of the optical calibration is also a goal, and it can be carried out either with deployed radioactive sources or with naturally present background sources. Finally, the outcome of the work is expected to lead into an improved measurement of neutrino-less double beta decay.

Initially, the focus will be on commissioning the calibration systems, especially the optical sources (the main one is a diffuser for N2-dye laser pulses) needed for energy response calibration, taking calibration data, and developing dedicated software for automated quality control. A second step is to develop methods to analyse the data and model as accurately as possible the light propagation in the detector and the collection efficiency of the array of PMTs, that is known to degrade over time.
To conclude, the analysis of events from natural radioactivity contaminants still present in the detector, will be used to validate and fine tune the calibrated energy response, since it has a uniform distribution more similar to the neutrino data.
The work will include also participation in in-situ activities in SNOLAB including, in the early stages, the commissioning of the calibration systems, and later on, data-taking and calibration data analysis.

Helioseismology and asteroseismology are powerful observational methods that allow to drill the interiors of stars. Measuring oscillation frequencies allows one to constrain theoretical stellar models, i.e. estimate the mass of a star, its age, initial chemical composition or other related physical characteristics. The use of observational constraints sensitive to its interior is of the uttermost importance since i) some fundamental characteristics (e.g. the mass or the age) are mostly determined by the central physical state of the star, ii) the modelling of the surface layers is difficult and our models are much cruder (and hence unlikely to reproduce observations depending mostly on these regions). This second issue is at the heart of a long-standing problem in helio- and asteroseismology. Even though the stellar oscillations are sensitive to the stellar interior, they are still affected by the surface layers. It has long been recognized that there exist systematic differences between computed frequencies, based on our best solar models, and observed solar frequencies.

It is this issue we want to investigate in this program. Since it is believed that these differences arise from an improper treatment of the upper layers (top of the surface convective zone, interior/atmosphere boundary, atmosphere) of stars, we want to test alternative physical models that might reinstate an agreement between theory and observations. This would in turn be extremely useful in order to calibrate properly theoretical models using solar data and then apply them to other stars. It has been often conjectured that the current modelling of convection could be the most important factor leading to the exiting disagreement. Therefore, we will explore some parametric models for convection that will allow to tune finely the efficiency of the process, as well as its characteristic length scales. To that effect, we will use Bayesian computational methodologies in order to explore the multi-dimensional spaces of parameter underlying these convection models.

Gauge symmetries play a fundamental role in the Standard Model (SM) of particle physics. Despite the enormous success of the SM in explaining many experimental results, including the recent discovery at LHC of a scalar particle with Higgs-like properties, there are several reasons to believe that the model should be extended by adding new particle content and, consequently, by enlarging its symmetries. Indeed, in the SM, one cannot find an explanation for neutrino masses or the matter-antimatter asymmetry observed in the Universe; there is no rationale for the fermion mass hierarchies, and it does not provide a dark matter candidate, among other theoretical drawbacks.

This project aims at studying and developing several phenomenological and theoretical aspects of gauge theories beyond the SM. In particular, we shall focus on SM extensions with new gauge and/or flavour symmetries and their phenomenological implications (e.g. Higgs and neutrino physics, baryon asymmetry, dark matter). In the context of Grand Unification, such extensions are well motivated. Some theoretical issues to be considered are gauge anomaly cancellation, unification of the gauge couplings, and fermion mass and mixing generation.

Extensive air showers develop in a complex way as a combination of electromagnetic cascades and hadronic multiparticle production. It is necessary to perform detailed numerical simulations of air showers to infer the properties of the primary cosmic rays that initiate them. But simulations are a challenge since the number of charged particles in a high energy shower can be enormous. The design of algorithms is also hampered by limited knowledge of interaction cross-sections and particle production at high energies. Thus, development of models to unveil the dominant mechanisms that govern the cascades phenomenology are necessary in order to access the details of the high energy interactions.

The hadronic cascade consists of a bulk of low energy mesons, mainly pions, of energies reachable by man made accelerators and fewer high energetic particles, leading barions and other mesons that yet carry a large fraction of the total energy. The energy and momentum of these leading particles depend on the details of the high energy interaction models, and determine the lower energy production of the bulk of mesons though the inelasticity, partition function and multiplicity.

The Pierre Auger Observatory consists on a surface detector array (SD), sampling the particles - namely muons, electrons and photons- arriving at ground in an area of 3000 km² in the Argentinean Pampa, and a fluorescence detector (FD) imaging the development of the electromagnetic component of the shower in the atmosphere. The hybrid nature is a crucial feature of the observatory, each sub-detector giving complementary information. The observatory is also to deploy a series of complementary detectors that include: antennas for radio detection, a second detector acompanying all Cerenkov tanks (yet to be decided the specifics, the so called B2015), a set of buried scintillators (AMIGA), and an engeneering of segmented RPCs beneath the Cerenkov tanks (MARTA engeneering array).

The work program of this thesis consists on the study of the different mechanisms that play a role on the development of the shower and give rise to the observables that Auger can measure. The objective is to model the cascade and gain insight into the phenomenology of the shower development with the aim to extract constraints to high energy physics models and composition of the primary beam.

The recent discovery of the Higgs Boson at the Large Hadron Collider appears to support the idea that the universe underwent, in its early history, a series of symmetry-breaking phase transitions and that, as a consequence, networks of topological defects could have been generated. These defect networks, although formed in the early universe, are expected to survive throughout the cosmological history, potentially leaving behind a plethora of observational signatures. The study of cosmic defects and their signatures, then offers an insight into the physics of the early universe. Compellingly, the recent suggestion that fundamental strings and 1-dimensional Dirichlet branes – the fundamental objects of Superstring theory – may play the role of cosmic strings, extends this possibility towards very early cosmological times into energy scales far beyond the reach of current particle accelerators.

Surveys of the cosmological 21cm signal – using SKA and LOFAR – will probe the matter distribution of the universe during the “dark ages”, potentially unveiling the role of small-scale density perturbations generated by cosmic strings and other cosmic defects in structure formation. On the other hand, the gravitational wave background will be probed with unprecedented sensitivity by a new generation of gravitational wave experiments (e.g. eLISA, LIGO) and the Cosmic Microwave Background B-mode polarization power spectrum will be determined with unprecedented precision by present and future missions such as Planck and CMBPol. Together these provide new observational windows for the study of cosmic defects and their associated vector and tensor perturbations which will be extensively explored in this project. The opportunities to gain information about the physics of the early universe through the search for topological defects are, thus, manifold.

This PhD project aims at significantly improving current constraints on cosmic defects, by making use of the latest data and realistic numerical and semi-analytical models for defect network evolution. Particular emphasis will be given to the gravitational wave background generated by cosmic strings and domain walls and its potential impact on the B-mode polarization of the Cosmic Microwave Background (CMB), as well as to the characterization of specific string signatures on the 21cm background and their impact on reionization history. The potential role of domain walls as seeds of space-time variations of fundamental couplings shall also be investigated, taking full advantage of the window opened by a new generation of high-resolution ultra-stable spectrographs such as ESPRESSO.

As a result of the launch of the CoRoT and Kepler satellites, the astronomical community has, today, exquisite asteroseismic data on thousands of red giant stars. The analysis of just a fraction of these data has already led to a number of very exciting new results, published in high-impact journals, such as Nature and Science. Moreover, given the recent approval by ESA of the mission PLATO2.0 (launch around 2023), it is expected than in a decade the number of red giants with detected oscillations will increase by orders of magnitude. To exploit this large observational sample of stars, further development of asteroseismic theoretical tools is required. In particular, it is imperative that we have tools capable of modelling the pulsations in large grids of red giant models, covering a wide parameter space (in mass, age, metallicity), in a reasonable amount of time. In this context, the main goal of this project is to develop a new linear adiabatic pulsation code, significantly more efficient than those currently available, that may be applied to large grids of red giant models, necessary to fully exploit the available data. Along with the characterization of the red giant populations based on the data already available, the proposed tool will constitute a magnificent step forward towards the preparation for the exploitation of the data that will be acquired by the PLATO2.0 mission.

This project will focus on fundamental phenomena that are the reason of the existence of our world as it stands today: it relies on peculiar properties of nuclei and ultimately the dynamics of quarks and gluons in the Quantum Chromodynamics (QCD) at the microscopic level.

The project aims at investigating the behavior of strongly interacting matter at finite temperature and chemical potential in a strong magnetic background. The investigation of QCD phase diagram under extreme conditions and the influence of strong magnetic fields, is a very recent and active field of both theoretical [1-3] and experimental studies [4].
Understanding matter under extremely intense magnetic ﬁelds is one of the most interesting topics in modern physics due to its relevance for studies involving compact objects like magnetars [5], measurements in heavy ion collisions at very high energies [6,7] or the ﬁrst phases of the Universe [8].

We will consider the influence of the magnetic field on the deconfinement and on the chiral symmetry breaking, which are two of the most important features of QCD, and on the behavior of the light scalar and pseudoscalar mesons.

This investigation has important implications in:
1 - Heavy ion collisions programs;
2 - Astrophysics, namely in the understanding of the interior of compact stellar objects such as neutron stars (a place of the Universe where dense QCD matter is realized and from which observations can extract information about the properties of QCD);
3 - Anchoring our empirical understanding of the origin of matter in the Universe to a more fundamental level.

The PhD candidate will be integrated in the CFC-Coimbra in an international team (with collaborations in France and Brazil) which has a long and vast experience dealing with the study of the phase diagram from several points of view (from lattice QCD (LQCD) calculations to building and use of effective models [9] for the study of the strong interaction and compact stars [10]).

[1] M. Ferreira, P. Costa, D. P. Menezes, C. Providência, N. N. Scoccola, Phys. Rev. D 89, 016002 (2014).
[2] P. Costa, M. Ferreira, H. Hansen, D. P. Menezes, C. Providência, Phys. Rev. D 89, 056013 (2014).
[3] M. Ferreira, P. Costa , O. Lourenço, T. Frederico, C. Providência, Phys. Rev. D 89, 116011 (2014).
[4] R. C. Duncan and C. Thompson, Astrophys. J. 392 , L9 (1992); C. Kouveliotou et al., Nature 393 , 235 (1998).
[5] V. Voronyuk, et al, Phys.Rev. C 83, 054911 (2011).
[6] V. Skokov, A. Y. Illarionov, and V. Toneev, Int. J. Mod. Phys. A 24 , 5925 (2009); V. Voronyuk, V. Toneev, W. Cassing, E. Bratkovskaya, V. Konchakovski, and S. Voloshin, Phys. Rev. C 83 , 054911 (2011).
[7] D. E. Kharzeev, L. D. McLerran and H. J. Warringa, Nucl. Phys. A 803 , 227 (2008).
[8] T. Vachaspati, Phys. Lett. B 265 , 258 (1991); K. Enqvist and P. Olesen, Phys. Lett. B 319 , 178 (1993).
[9] P. Costa, O. Oliveira and P. J. Silva, Phys. Lett. B 695, 454 (2011).
[10] D. P. Menezes, M. B. Pinto, L. B. Castro, P. Costa, C. Providência, Phys. Rev. C 89, 055207 (2014).

The idea to unify three of the four interactions observed at low energy, namely the strong, electromagnetic and weak interactions, has attracted many theorists during the last decades. In GUTs not only one get the unification of the gauge couplings but also the Standard Model (SM) fermions belong to larger GUT multiplets. Thus, GUTs models are a beautiful framework for studying fermion masses and their mixings. Because of matter unification, proton decay is one of the direct consequences of grand unification. Another beautiful aspect of many GUT models is the generation of neutrino masses, since neutrinos remain massless in the SM.

When such GUT models are realised within the framework of supersymmetry (SUSY) the issue of proton decay is problematic, because new processes (dimension-five operators) involving scalar SUSY partners of the fermions dominate and therefore proton decays faster. Orbifold GUTs can indeed be an attractive solution to this problem. An orbifold is a Higher-dimensional space-time obtained by dividing a manifold with some discrete symmetries, having fixed points, which transform into themselves under the discrete transformations. One of the main features of orbifold compactifications is to allow the breaking of the GUT gauge symmetry to the SM gauge group in an simple way. In particular, the breaking of the GUT symmetry automatically yields to the required doublet- triplet splitting of Higgs fields. Several SU(5) models have been constructed in five dimensions (5d), whereas six dimensions are required for the breaking of SO(10).

During this project the student will learn aspects of group theory, fermion masses in GUT framework including extra flavour symmetries, Textures zeroes, Proton decay, CP violation and other aspects of flavour physics. Special emphasis will be given to orbifold SO(10) GUT models in 6D space-time and their phenomenological implications.

The electromagnetic and weak forces that shaped the Universe we see today are part of a more fundamental electroweak interaction which dominated the early moments after the Big Bang. In the Standard Model theories of Particle Physics, electroweak symmetry breaking which led to the separate interactions is described by the Higgs mechanism. The Higgs boson was discovered by the ATLAS and CMS experiments at CERN’s LHC collider and constitutes experimental evidence for this mechanism. But there is still much that is unknown about electroweak symmetry breaking and the properties of the Higgs boson. The experimental focus has thus moved to the precise measurements of the Higgs boson properties, since they have deep implications on scenarios of New Physics beyond the Standard Model. In particular, measurements of the associated production of a Higgs boson with a top quark pair – which has not yet been observed – are the only way to directly access the top Yukawa coupling between Higgs and top. This is a very important parameter, since the high mass of the top quark implies that it may play a fundamental role in the underlying dynamics of the electroweak symmetry breaking and the stability of the Universe.
The proposed project aims at making the first observation of the associated Higgs boson production with a top quark pair, ttH, using the ATLAS experiment at the LHC collider. It will imply the analysis of proton-proton collisions at a centre of mass of 13 TeV during the LHC run II, from 2015 to 2018, using advanced computing and simulation of the complex ATLAS detector. This is a challenging analysis at the cutting edge of Particle Physics research, and will require LHC data from several years. From this data it will be possible to make a first observation of the ttH process and a determination of the top Yukawa coupling constant. Any deviation of this value from the Standard Model expectation will indicate the presence of New Physics. The student will take part in ATLAS data taking operations and physics analysis activities, with frequent trips to CERN to participate in Control Room shifts and collaboration meetings.

The subject of this thesis is the search for Higgs production in association with top quark pairs. The top quark pair produced in association with the Higgs boson – ttH channel - with subsequent Higgs decays is interesting because the rate of this process depends on the couplings of the Higgs boson to the top quark as well as to the final state searched for. Measuring these couplings will help to determine whether the new boson observed at the Large Hadron Collider (LHC) with a mass of 125 GeV is indeed the Higgs boson with SM properties.

In particular, the work plan is to analyze processes with top quarks in the final state. Top quarks are mostly produced in pairs at the LHC and, according to the SM, each one decays to a W-boson and a b-quark. Depending on the decay mode of the W-boson, either leptonic or hadronic, the final state may contain two, one or no leptons.

The Sudbury Neutrino Observatory (SNO) is a large volume neutrino detector located in the SNOLAB underground laboratory in Canada. SNO has demonstrated that solar neutrinos do change flavor and thus have a small, but non-zero, mass. The SNO+ experiment will replace SNO's heavy water target by liquid scintillator, providing sensitivity to several new low energy neutrino physics measurements.
If it exists, the rare process of neutrino-less double-beta decay would prove that neutrinos are Majorana particles – their own antiparticles – and would allow the measurement of the absolute scale of neutrino masses. SNO+ will use the advantages of a large mass and very-low background detector to search for this process by loading large quantities of Tellurium in the liquid scintillator.
During all the phases, SNO+ will also detect anti-neutrinos from nuclear reactors and from the Earth's natural radioactivity, as well as galactic Supernova neutrinos.
The detector upgrade of the SNO+ experiment (scintillator purification system, new acrylic vessel support, new calibration systems, etc..) is currently being completed at SNOLAB, in Canada. Data taking is expected to start in late 2015. A short commissioning run period with pure liquid scintillator will be followed by the Tellurium-loaded phase. In later phases – with pure liquid scintillator again – SNO+ will also be able to measure several components of the solar neutrino spectrum. The LIP group is responsible for several aspects of the calibration system – PMT and scintillator optical calibration, source insertion mechanism – as well as the anti-neutrino analysis.

The broad scope project's goals are to obtain the first neutrinoless double-beta decay limits (or positive measurement) with SNO+. The quality of the measurement is crucially dependent on achieving the lowest possible backgrounds, either by removing contaminants from the scintillator mixture, or through the use of short-lived isotope background events identification methods. The workplan for this project will target this aspect and focus on the development of coincidence techniques. The goal of high sensitivity demands a high efficiency > 99.99% to reconstruct these backgrounds. In order to achieve this goal, the tagging efficiency of bismuth-polonium coincidence events from the natural U/Th decay chains has to be fully determined. Time-window and spatial cuts will be tested using Monte-Carlo simulation and the full performance of the method will be validated with data when available. A measurement of the tagging inefficiencies due to the detector dead-time will also be performed and serve as input to the measurement of the total background from the U/Th chain seen in the detector.
Finally, in order to extract the double-beta decay half-life (and corresponding effective neutrino mass) limit, the knowledge of the backgrounds obtained previously, and models of the detectors response obtained by calibration, will be combined in the full data analysis. This will be carried out with maximum likelihood methods that will use the reconstructed energy, position and particle identification information, in addition to constraints from calibration and independent background analyses.
This project will include simulation and analysis of simulation data as well as the water and scintillator data. In the early stages of the thesis, a participation to the in-situ activities in SNOLAB or on the commissioning of the calibration system may also be required.

The discovery of the Higgs boson during the first run of the Large Hadron Collider (LHC) was a crucial point for the consolidation of the Standard Model (SM) of particle physics. Nonetheless, the exact nature of the electroweak symmetry breaking mechanism is not yet determined. In particular, the SM violates the concept of naturalness when extrapolated to energies above the electroweak scale, since fine tuning is required to compensate the quadratic divergences of the fundamental scalar fields. Proposed models of physics beyond the SM typically address the naturalness problem by postulating a new symmetry, as for example, supersymmetry. Alternatively, the symmetry could be a spontaneously broken global symmetry of the extended theory. Examples of models implementing this idea are Little Higgs and Composite Higgs models, which predicts the existence vector-like quarks, defined as colour-triplet spin-1/2 fermions whose left- and right-handed chiral components have the same transformation properties under the weak isospin gauge group. Such quarks could mix with like-charge SM quarks, and the mixing of the SM top quark with a +2/3 vector-like quark could play a role in regulating the divergence of the Higgs mass-squared.

The ATLAS and CMS collaborations have performed a comprehensive search program using the first run of the LHC with proton/proton collisions at a centre of mass energies of 7 and 8 TeV, collected in 2011 and 2012, respectively. Such searches showed no evidence for physics beyond the SM, but vector-like quarks with masses above ~800 GeV could not be probed yet. The increased centre of mass energy and luminosity at the run-II of the LHC will allow to continue the vector-like search program, and masses above 1 TeV are expected to be probed in both pair and single production modes.

The present proposal foresees the integration of the applicant in the Portuguese ATLAS group, continuing the group work in the search for new vector-like quarks in multi-lepton topologies. A new analysis strategy will have to be developed in order to deal with the challenging pile-up conditions expected for the run-II data. The evaluation of systematics uncertainties, testing new strategies to control them, and a close collaboration with the phenomenological community in the interpretation of the experimental results will be crucial to fully exploit the potential of the new LHC data.

Rare processes are a very promising means for detecting physics beyond the standard model (BSM). The subject of the thesis is the search and study of B meson rare decays. The project will be carried out in the framework of the CMS experiment at CERN’s LHC.

The decays of neutral B mesons into muon pairs, sometimes dubbed golden rare decays, are particularly sensitive to new physics. They constitute flavor changing neutral currents (FCNC), being further disfavored by spin conservation. In this way, the decays are highly suppressed in the standard model and proceed only through higher-order (loop) diagrams, probing the underlying fundamental theory at the quantum level. Sizable enhancements of the decay rates are nevertheless predicted in the context of common classes of BSM scenarios, including supersymmetry (SUSY) and models with extended Higgs sectors. They constitute for this reason most promising probes for revealing the presence of new physics, and for characterizing it.

Given their relevance, B→ μμ decays have been actively searched for over the past few decades, by various experiments at different accelerators. Sufficient experimental sensitivity is now attained for the first time at the LHC. The CMS experiment has unique capabilities to explore the dimuon signature and to carry out this important search. Analysis of the LHC Run I data has led CMS and LHCb to recently report independent evidence for the Bs rare decay [1]. The primary goal of the thesis project is to pursue and extend the search for the B→ μμ rare decays with CMS, exploring the LHC Run II dataset. Initially, the Bs signal will be established, and, as data accumulate, used in further sensitive measurements. Then, a dedicated search for the even rarer Bd decay will be designed and implemented.

The proposal foresees the integration of the applicant in the CMS B Physics Group, which is currently co-led by LIP. The applicant will play a central role in this flagship LHC analysis.

[1] PRL 111 (2013) 101804; PRL 111 (2013) 101805; CMS-PAS-BPH-13-007 (update to be published in Nature)

The top quark is the heaviest elementary particle known, with a mass close to the electroweak symmetry breaking, and it can provide clues about the symmetry breaking and the Higgs mechanisms. It is thus an excellent object to test the Standard Model of Particle Physics (SM). There is an important effort to study the top quark properties, like its mass, production cross-sections, electric charge, spin, decay asymmetries, rare decays, etc...

Deviations from SM predictions of the production and decay properties of the top quark provide model-independent tests for physics beyond the SM. According to the SM, the top quark decays nearly 100% of the time to a W boson and a b quark. Flavour changing neutral current (FCNC) decays are forbidden at tree level by the GIM mechanism and are allowed at one-loop level with a branching ratio of the order of 10^-14. Several SM extensions predict a higher BR for top quark FCNC decays, such as 10^-4. The search for FCNC decays can be done using effective operators such as 4-Fermion, and provide thus a way for verify the validity of the SM and test the existence or restrict SM extensions.

This research program will be developed within the Portuguese ATLAS group and aims to search LHC data (collected by the ATLAS detector) for single top quark production via FCNC 4-Fermion operators or to set 95%CL limits in the absence of signal.

The minimal supersymmetric extension of the standard model (MSSM) requires the introduction of two Higgs doublets in order to preserve supersymmetry. This leads to the prediction of five elementary Higgs particles: two CP-even (h, H), one CP-odd (A), and two charged (H±) states. The lower limit on the charged Higgs boson mass is approximately 80 GeV as determined by LEP experiments.

The study aims at the search for a charged Higgs bosons, where the Higgs boson mass is either lighter or heavier than the top quark mass. If the mass of the charged Higgs boson is smaller than the difference between the masses of the top
p and the bottom quarks, the top quark can decay via t → H+b. In the case of a heavy charged Higgs boson, the leading order QCD process gb→tH± gives a sizable production cross section at the LHC. The charged Higgs boson either decays through its dominant decay mode, H± → t ̄b, or through its leading sub dominant decay mode, H± →τ±ντ, which accounts for a branching fraction of ∼10% for tan β(>5-10). The candidate is expected to work in a team with a group of researchers.

Searches for new physics in this channel can be significantly improved over the current limits with the additional data, and with improved analysis techniques.

Measurements of the Cold Dark Matter (CDM) indicate that if Supersymmetry (SUSY) is a symmetry realized in nature, the lightest supersymmetric partner of the tau lepton (stau) might be one of the lightest SUSY particle producible at the LHC. The production rate for stau is enhanced in several SUSY scenarios, further increasing the chances for this particle to be observed at the LHC.

The aim of this search is to search for the direct pair production of the stau lepton. It will be performed in the leptonic and hadronic decays of the tau, plus additional missing energy. This search will benefit from the expertise of the LIP CMS group in tau leptons.

The study aims at the search for the supersymmetric (SUSY) partner of the top quark (stop) with the CMS experiment at the LHC. SUSY partners of quarks & gluons, namely squarks & gluinos, are among the most accessible SUSY particles at the LHC. For every quark, the mass splitting between pairs of squarks is proportional to the Standard Model (SM) quark mass. Since the top is the heaviest SM quark, the lightest stop may be the lightest squark, thus the most easily observable at LHC. Stop searches are at present among the most exciting searches at the LHC.

The search for direct stop pair production will be led in the “lepton + missing energy + jets” final state. The energy reach & the expected integrated luminosity of the LHC for the coming years will allow a search for stop in mass regions yet unexplored, and across 3 different decay modes, rendering this search as model independent as possible.

The study aims at the search for the supersymmetric (SUSY) partner of the top quark (stop) with the CMS experiment at the LHC. SUSY partners of quarks & gluons, namely squarks & gluinos, are among the most accessible SUSY particles at the LHC. For every quark, the mass splitting between pairs of squarks is proportional to the Standard Model (SM) quark mass. Since the top is the heaviest SM quark, the lightest stop may be the lightest squark, thus the most easily observable at LHC. Stop searches are at present among the most exciting searches at the LHC.This search targets a scenario where the mass difference between the stop & the Lightest Susy Particle (LSP) is very small. The measure of the Cold Dark Matter (CDM) density gives a high preference to such compressed mass spectrum.

This search will be led in the “lepton + missing energy + jets” final state, taking advantage of the expertise of the LIP CMS group in the LHC data with this signature. The kinematic spectra of the physics objects being very soft, this search opens the possibility for an approach innovative & complementary to other stop searches.

In the next 5 billion years, the Sun will start to cool and
expand, becoming a Red-giant star. During this process, the Sun radii
will increase hundreds of times, and will engulf the orbits of the
inner planets. However, during this process the orbits of the planets
will also expand, and there is a possibility that they are never
cached by the solar envelope. Nevertheless, the orbital scattering may
also give rise to close encounters between the planets, which will
cause collisions between them or ejections from the Solar System.
During this Ph.D we want to study the simultaneous solar and orbital
evolution of the Solar System during the last stages of the solar
life. In particular, we wonder what will be the fate of the inner
planets, and, in particular, the final destiny of the Earth. We will
also apply our model to the already detected planets around Red-giant
stars.

COMPASS is a high-energy physics experiment at CERN. Its purpose is the study of hadron structure, namely a better understanding of the spin structure of the nucleon.

In that view, data already collected by COMPASS in previous years of deep inelastic scattering of a muon beam off a polarized target offer a very interesting framework to the deep understanding of nucleon structure, addressing subjects like the gluon polarisation in the nucleon and the polarized parton distribution functions.

In particular, the strange quark polarisation puzzle is an interesting open topic.
The extraction of strange asymmetries, s↑↑(x) and s↑↓(x), coming from the two experimental spin configurations, parallel and anti-parallel, allows the measurement of both the spin independent and the spin dependent strange parton distributions, s(x) and Δs(x).
So far, the results on the measurement of Δs(x) are inconsistent because they are depending on the observed final state. As strange quarks are building blocks of kaons, one expects that the strange quarks polarization should be precisely measured in events where a kaon is detected. These studies are based on very reliable kaon identification, from the RICH detector of COMPASS.

Also the gluon polarisation will be addressed and it should use the more advanced tools like artificial Neural Networks or developing other techniques as genetic algorithms.

Adaptive-optics (AO), a technology at the crossroads of physics, mathematics, optics and electro-mechanics, partially corrects the image blurring of the Earth's atmosphere – a direct consequence of otherwise flat wave-front distortions undergone during propagation through a (weak) turbulent medium. AO recovers the angular resolution of the telescope (the ability to tell apart two objects, however close, proportional do D), i.e. overcomes the natural seeing when observing through turbulence and limits the tremendous sky-background contribution for improved sensitivity → reaching D^4. It uses a wave-front sensor (WFS) to measure distortions and a deformable mirror (DM) whose shapes are computed in real-time (RTC) to counter distortions and flatten the resulting wave-front. Modern AO systems routinely allow diffraction limited imaging — matching the limits set by optical theory — on 8–10m telescopes in the near-infrared. The next decade should see the application of this technique to 30–40m-class telescopes as well as to shorter wavelengths.

The wave-front information that can be extracted from a given number of photons is known from first principles. Such information accurately defines the “ideal” performance which can be reached by Adaptive Optics systems on ground-based telescopes [Guyon 2005]. Direct comparison between this ideal limit and the sensitivity offered by current wave-front sensing schemes reveals a huge performance gap.

The commonly used wave-front sensors in astronomical adaptive optics, such as Shack-Hartmann and linear Curvature, are very robust and flexible. However, they are poorly suited to high quality wave-front measurement – for low-order aberrations on 8 to 10m telescopes, they require ~100 to 1000 times more photons than more optimised wave-front sensing techniques. In one hand, they offer nearly ideal sensitivity at the spatial frequency defined by the sub-aperture spacing. On the other hand, they suffer from poor sensitivity at low spatial frequencies, which are most critical for wide-field tomographic AO systems employing lasers for the measurements of tilt and tilt anisoplanatism [Correia, JOSA-A 2013] modes and also on direct imagers of exo-planets and protoplanetary disks – projects SPHERE [Beuzit et al. 2008] and GPI [Macintosh et al. 2008].

Non-linear curvature wave-front sensing (nlCWFS) delivers outstanding sensitivity and high dynamic range by lifting the linearity constraint of standard curvature wave-front sensing. This is achieved by taking full advantage of diffraction, which encodes wave-front aberrations into patterns of diffraction-limited interference speckles. The high sensitivity and linear range of the nlCWFS comes at the price of a non-linear wave-front reconstruction step, which calls for innovative, fast and robust minimisation algorithms. This path has already been started in [Correia et al. 2013] using a modification to standard phase-retrieval techniques.

The main goal of this thesis is to investigate and propose a physics/optics-driven model approximation to beat down the massively computation involved in processing the measurements and estimate the corresponding wave-fronts.
This work will be done in collaboration with the Herzberg Institute of Astrophysics and the SCExAO team at the Subaru Telescope. Both have optical benches with a nlCWFS whose data will be used to compare model to reality. Also, the work will accompany the design, test and characterisation of a non-linear Curvature Wave-front Sensor at LAM – Laboratoire d'Astrophysique de Marseille and availability of potential candidates to spend time in Marseille is required.

Profile: Student with strong interest in optics/propagation, mathematical modelling, statistical physics, numerical simulations, data/signal processing. The work will accompany the design, test and characterisation of a non-linear Curvature Wave-front Sensor at LAM – Laboratoire d'Astrophysique de Marseille and availability of potential candidates to spend time in Marseille is required.

References:
Correia et al, Wave-front reconstruction for the non-linear curvature wave-front sensor, AO4ELT, (2013) http://dx.doi.org/10.12839/AO4ELT3.13290
C. Correia et al, Increased sky coverage with optimal correction of tilt and tilt-anisoplanatism modes in laser-guide-star multiconjugate adaptive optics, http://dx.doi.org/10.1364/JOSAA.30.000604

Key words: Hyperons, hypernuclei, hyperon-nucleon and hyperon-hyperon interactions, compact stars.

Strangeness adds a new dimension to the evolving picture of nuclear physics giving us an opportunity to study the fundamental baryon-baryon interactions from an enlarged perspective. The presence of hyperons in infinite (hypernuclear matter and neutron star matter) and finite (hypernuclei) nuclear systems constitutes a unique probe of the deep nuclear interior which makes possible the study of a variety of otherwise inaccessible nuclear phenomena, and, thereby, to test nuclear models. Furtheremore, there is a growing evidence that strange particles can have significant
implications for astrophysics. In particular, the presence of hyperons in the dense inner core of neutron stars is expected to have important consequences on the equation of state, structure and evolution of these compact objects. In this project we will study the properties of hyperons in infinite matter and hypernuclei. Our final scope is to relate hypernuclear and neutron star observables to the bare hyperon-nucleon and hyperon-hyperon interactions which, unfortunately, are not yet well constrained experimentally. To that end we will extend both microscopic and phenomenological approaches, usually used in the study of the properties of infinite nuclear matter and ordinary nuclei, to the hyperonic sector.

The general scope of this project is the study of the properties of
hyperons in infinite (hypernuclear matter and neutron star matter)
and finite (hypernuclei) nuclear systems by extending both microscopic and phenomenological approaches that are commonly used in the studies of the properties of infinite nuclear matter and ordinary nuclei. Our final goal is to relate hypernuclear and neutron star observables to the bare hyperon-nucleon (YN) and hyperon-hyperon (YY) interactions. The experimental difficulties associated with the short lifetime of hyperons and low intensity beam fluxes have limited the number of YN scattering events to less than one thousand, not enough to fully constrain the YN interaction. In addition, there is no data at all on the YY scattering. In the absence of such data, alternative information on the YN and YY interactions can be obtained from the study of hypernuclei and the properties of hyperons in neutron stars.

Specific objectives are:

1) Develop energy density functionals of hypernuclear matter starting from the most realistic NN, YN and YN interactions and study the consequences of hyperons in neutron stars paying special attention to the possible existence of a hyperon phase transition in the neutron star interior and the influence on it of the different terms of the functionals.

2) Extension of the Dirac-Brueckner-Hartree-Fock theory of nuclear matter to the hypernuclear matter case.

3) Systematic microscopic and phenomenological study of single- and double-lambda hypernuclei.

The Pierre Auger Observatory, presently the world's largest cosmic-ray detector, detects the extensive air-showers (EAS) initiated by the interaction of ultra high energy cosmic rays (UHECR) in the Earth atmosphere at centre-of-mass energies up to 100 TeV, well above that of the LHC.

The Observatory, located in the Argentinean Pampa, consists on a surface detector (SD) array of 1600 water Cherenkov tanks, sampling the shower secondary particles arriving at ground in an area of 3000 km² and a fluorescence telescopes detector (FD) imaging the longitudinal development of the electromagnetic component of the shower in the atmosphere.

The data collected so far allowed to establish important breakthrough results at the highest energies: the suppression of the flux and hints of anisotropy of the cosmic rays arrival directions. Also, several possible scenarios for the origin of the UHECR were ruled out, favouring astrophysical acceleration mechanisms.

Nevertheless, open questions remain to be solved, in particular about the origin and nature of the UHECRs. Currently, all under carried primary mass composition studies suggest either an unexpected astrophysical scenario or changes on the hadronic interaction physics at the highest energies. The answer to this puzzle implies a stronger knowledge about the shower physical mechanism, specially about the EAS muon content. This later quantity is directly related to the hadronic interactions that occur during the shower development and might help to break the current degeneracy of the shower observables between the primary mass composition and the hadronic interactions.

The Auger Collaboration is presently studying different options for the upgrade of the detector to improve the air-shower measurement.
In particular, the enhancement of the capabilities of the surface array for the identification of the muons produced in the EAS is a key aspect of the upgrade. In this context the LIP group is leading the MARTA project, proposing an innovative concept for the muon detection in Auger.
MARTA (Muon Auger RPC for the Tank Array) consists basically of robust RPCs (Resistive Plate Chambers) deployed under the tanks of the SD array, that will measure the muons on an event-by-event basis with high efficiency, and high timing and spatial accuracy.
These unique characteristics will further allow to measure simultaneously the muon signals in the tanks and in MARTA, providing a powerful tool to inter-calibrate both detectors and to monitor important parameters of the tanks.
Several full scale prototypes are already installed and taking data in the Auger Observatory: a muon telescope, consisting of two RPCs placed on the top and the bottom of one tank, has been operating for several months at the Observatory; two MARTA stations are being deployed in the field and starting to take data.

A MARTA Engineering Array (EA), consisting of about ten MARTA stations, will start to be deployed in the SD array during 2015.
The successful operation of the EA will be of the utmost importance for the proof-of-concept of MARTA.
The selected candidate will be involved in the activities of the LIP/Auger group, in particular those related with the Engineering Array.
Performance and optimisation studies will be carried out by using state-of-the-art Monte Carlo simulations of the air-showers propagation and of the detectors at ground. The candidate is also expected to take part in the detector installation and commissioning.
An important part of the work will consist in the analysis of the data taken by the EA and the comparison with the simulation results.
This interplay between simulations and real data will be of great relevance both in the validation of the existing MARTA simulations and
for possible improvements in the final detector design.
Moreover, the first data of the EA can be also used to test our physical knowledge about the shower, as this array will collect mainly events with a centre-of-mass energy compatible with those of the most energetic man-made accelerator, the LHC. Therefore, the candidate is also expected to participate in the creation of tools to reconstruct showers.

Recent observations of the highest redshift quasars and radio galaxies pinpoint the early growth of supermassive black holes (SMBH) that trigger the formation of active galactic nuclei (AGNs) at redshifts greater than 7. It is anticipated that radio emission can be detected from such early AGN, although its characteristics are still quite undeterminated. The importance of such detection, however, is extremely high. It will: (a) provide us with a lighthouse that reveals the physics of the first accretion episodes to the first SMBHs in the Universe; (b) allow the direct study of the neutral gas throughout the Epoch of Reionisation itself with the next generation of radio telescopes, through the observation and study of the HI 21cm forest against such early AGN; (c) allow us to trace the early growth of Large Scale Structure in the Universe. After decades of laborious work, trying to understand the deepest radio observations, the conditions are now finally right to develop a project that can make us understand where are the “first radio galaxies” and how to find them with upcoming radio telescopes.

In this thesis, the student will understand the current knowledge about powerful radio sources and their evolution out to the very highest currently observable redshifts (z~5-6). He will assemble different models of structure formation that handle the formation and evolution of the first SMBH in the Universe and confront theory and observations. With this process, he will aim to (a) identify flaws and difficulties in the models of structure formation, pinpointing improvements needed in the light of the deepest radio observations; (b) predict the properties and observable characteristics of the first radio-bright SMBHs, with the particular objective of improving the SKA development (frequency coverage, sensitivity and resolution, for example) towards the detections of this first generation of radio galaxies. Implications for the upcoming generation of deep radio surveys like EMU (Norris et al. 2011) and WODAN (Rottgering et al. 2011) will be also considered within this thesis.

What are the physical drivers of galaxy formation and evolution? How much (and why) did galaxies like our own change across cosmic time (e.g. metallicities, dynamics)? When, how and through which physical mechanisms are galaxies “quenched”? In order to make progress, the student will explore our unique, large surveys that have yielded 1000s of galaxies (similar to the Milky Way), selected in the same way across the last 11 billion years (with WIRCam/CFHT and WFCAM/UKIRT telescopes). These are ideal samples to study the metallicities, dust extinction and rotation curves/dynamics of “typical” star-forming galaxies and how these have evolved from the peak of the star-formation history (z~2.5) till today. By using KMOS (observations already started and thus all data is guaranteed both as PI and as part of GTO collaboration), the student will be able to gain unprecedentedly detailed information on a large sample of galaxies. KMOS, with its 24 Integral Field Units (IFUs) allows to target up to 24 galaxies at the same time, obtaining an image and a near-infrared spectrum for each pixel. This is a unique opportunity to map the distribution and intensity of star formation, dynamics and metallicity on ~4 kpc scales and address (and to fully interpret them): (i) What is the fraction of primitive disks, spheroids and mergers? (ii) Is the distribution of star formation at high-z more centrally concentrated than comparably luminous/turbulent galaxies at z~0? and iii) Are chemical abundance gradients weaker or stronger than local spiral galaxies and do those change with time? Answers to these questions using our well selected samples will provide some of the strongest tests/constraints to the most sophisticated models of galaxy formation and evolution. By selection, all of the targets have known Hα fluxes and all are sufficiently bright so their resolved properties can be recovered and the survey efficiency will be >95% (GTO observations already yielded samples of ~400 galaxies). The results will be fully compared and contrasted to the best local IFU surveys (including artificially redshifting a variety of local galaxies and fully addressing biases and systematics), and will be interpreted using our unique 3D modelling capabilities developed at CAUP. Another unique aspect of this project is that there are significant over-densities in the very large samples of Hα emitters, and thus, with KMOS, the student will be able to confirm and characterise the high redshift structures, derive accurate metallicities, measure the mass-metallicity relation, obtain Balmer decrement extinctions and identify AGN for a sample of hundreds of Hα-selected galaxies and investigate if the environment plays a role in setting these galaxy properties.

The featureless appearance of bulges in Hubble-type galaxies has for decades sustained the view that these high-surface brightness spheroidal components are largely ``simple'' in terms of their assembly history, formed on a short timescale early on, and having experienced little evolution over the past several Gyr.
However, our early understanding of bulges as essentially scaled ellipticals has undergone a substantial revision over the last years. It is now recognized that central luminosity components that closely resemble classical bulges can also form over much longer timescales through disk instabilities and ensuing star forming activity at the centers of galaxies. The nature and formation history of these “pseudo-bulges” is enigmatic and of considerable relevance to our understanding of the structural and spectrophotometric evolution of galaxies in general.

This PhD project aims at a spatially resolved investigation of the star formation- and chemical enrichment history of pseudo-bulges. A unique aspect of its methodology is the combined application of surface photometry and spectral population synthesis to a large sample of galaxies from the Calar Alto Legacy Integral Field spectroscopy Area survey (http://califa.caha.es) with the goal of conclusively addressing the star formation history (SFH) and the chemical abundance patterns of pseudo-bulges. One of the central questions to be investigated is whether pseudo-bulges form in a quasi-continuous manner over several Gyrs of galactic evolution and their SFH can be parametrized through a simple functional form involving integral or structural properties of their host galaxy (e.g., total stellar mass; central surface brightness and exponential scale length of the underlying disk). Additionally, this project will include a comparative study of pseudo-bulges and classical bulges with the goal of the identification of new empirical discriminators between them and yield robust observational constraints to theoretical models of pseudo-bulge formation and evolution.

The field of extrasolar planets research is teaming with activity. Next year we will celebrate the 20th anniversary of the discovery of the first planet outside our system, and yet we count already over 1700 confirmed planets and hundreds of candidates to confirm. With a fast-growing pace and a bright future ahead guaranteed by large number of ongoing and planned projects, it presents itself as the astronomy topic of the change of the century.

As the planetary zoology continue, several interesting trends appear. For instance, it is a well-established fact that stellar metallicity plays an important role on the formation of planets, especially for massive ones. Interestingly, metallicity also has a strong impact on the evolution and orbital architecture of the planets. Several remarkable observational results can be outlined from the recent studies, which are still waiting for a solid explanation:

i) planets in the metal-poor systems form/evolve differently: they form farther out from their central star and/or they form later and do not migrate far,
ii) low-metallicity stars have a deficit of eccentric planets between 0.1 and 1 AU when compared to their metal-rich counterparts, because of either a less effective planet-planet interactions or due to the self-shadowing of the disk by a rim located at the dust sublimation radius (∼0.1 AU).

Along the same line, planet-planet and planet-disk gravitational interactions emerge as important orbit-shaping processes to be explored for a better understanding of the evolution of planets. With this application we propose to study the impact of stellar metallicity on the orbital evolution of planetary systems from the observational point of view and to develop new simulations in which we consider the effect of disk and/or a companion planet's presence on the planetary parameters.

This PhD is a joint project between Universidade de Aveiro and Centro de Astrofisica da Universidade do Porto (CAUP). The successful applicant will be involved in the activities of the two institutes, and collaborating closely with other researchers other than the proposed supervisors, such as Pedro Figueira.

The study Extensions of the Higgs sector of the Standard Model, with special emphasis on :

i) Mechanisms for the natural suppression of Flavour Changing Neutral Currents ( FCNC )

ii) The use of weak basis invariants in the study of the physical implications of Multi-Higgs extensions

iii) The study of new Sources of CP Violation and their phenomenological implications both in the quark and lepton sectors.

Top quarks are primarily produced in pairs at a hadron collider. In the framework of the Standard Model (SM), each top quark decays into a W and a b quark. The top quark pair events can be characterized by the decays of the two W bosons. Top quarks are abundantly produced in proton-proton collisions at the LHC, and constitute the main background to searches for New Physics. A , and a good understanding of the top quark events will allow a more sensitive reach into the realm of searches for BSM processes.

The work will focus will focus on measuring studying the properties of the top dilepton channel to measure the heavy flavour content of top quark events. Due to the higher center-of-mass energy during Run2 (13-14 TeV), further studies of additional b-jets produced in association with top quark pair events are also foreseen. The link between b-quark association to top events, and the possibly large content of heavy flavour in BSM final states will be used to further characterize the data, with the goal of discriminating between SM and BSM processes. An anomalous heavy flavor production is directly “visible” in this study. Deviations from SM predictions will indicate evidence for New Physics.

Adaptive Optics (AO) is a technique that currently equips most of the ground-based astronomical telescopes of classes 3-10m and will be at the heart of the future 20-40m-class telescopes.

AO enables to correct the effects induced by atmospheric turbulence, which affect the telescopes’ resolution and hence image quality. Introduced in the 1990s, AO systems became tomographic, allowing the analysis of the 3D volumetric turbulence needed to achieve wide-field correction.

Tomography is a linear, compute-intensive process requiring inverse-problem solvers. Bayesian approaches reach optimality but are deeply dependent on knowledge of the turbulence strength, scale, layer number and location, wind-speeds, etc along the lines of sight. Such parameters are commonly identified from optical data (scintillation, wave-front gradients) exploiting the angular correlation of signals – SCIDAR and SLODAR-like methods. Tomographic AO systems offer a wealth of information from which an enhanced processing can be envisaged. The precision required for next-generation instrumentation is also challenging to achieve.

A promising method to be used complementary to the built-in SLODAR method consists in the enhancement of existing identification algorithms using principles of synchronous detection in the spatial-frequency domain and its generalisation to tomographic, multi-sensor systems.
Applications foreseen are for Multi-Object AO systems – in particular Raven the science and technology demonstrator installed at the Subaru 8m telescope – and in general for wide-field AO systems and planet imagers.

Profile: Student with strong interest in mathematical modelling, statistical physics, numerical simulations, data/signal processing.

References:
C. Correia et al, Static and predictive tomographic reconstruction for wide-field multi-object adaptive optics systems, JOSA-A 2014 http://dx.doi.org/10.1364/JOSAA.31.000101
Olivier Lardière, David R. Andersen, Colin Bradley, Kate J. Jackson, Reston Nash, Darryl Gamroth, Célia Blain, Przemek Lach, Jean-Pierre Véran, Shin Oya, Yoshito Ono, Carlos M. Correia, Kim Venn, Yutaka Hayano, Hiroshi Terada, Masayuki Akiyama, Multi-object adaptive optics on-sky results with Raven SPIE Astronomical Telescopes + Instrumentation, Jun 2014, http://dx.doi.org/10.1117/12.2055480

Experimentally, free quarks or gluons were never observed. This empirical fact is called confinement and it is a manifestation of the non-perturbative regime of QCD. The perturbative solution of Quantum Chromodynamics is unable to accommodate confinement and other "non-perturbative" features associated with the theory.

The formulation of QCD on a spacetime lattice allows to access its non-perturbative dynamics from first principles, by means of computer simulations. However, any simulation is plagued with finite volume and finite lattice spacing effects which have to be removed for a reliable determination of the quantities of interest.

The computation of the correlation functions of the fundamental fields is an important task still to be finished using lattice simulations. The correlation functions encode the full dynamics of QCD. In a recent past, some basic Green's functions, such as gluon, ghost and quark propagators, have been studied by several research groups. However, the removal of lattice artifacts still remains to be done in a systematic way.

The project, to be developed in collaboration with the lattice QCD group at the University of Lisbon, aims to compute the quark propagator and quark-gluon vertex free of lattice artifacts at zero and at finite temperature. The project will profit from the new high performance computer facilities currently under instalation at the University of Coimbra and computer time available through PRACE projects. These correlation functions encode the non-perturbative nature of QCD related to the confinement and chiral symmetry breaking mechanisms. Furthermore, they are important correlation functions to be used in Dyson-Schwinger and Bethe-Salpeter equations to access relevant phenomenological properties of hadrons. It is therefore of paramount importance to have access to good quality data for the correlation functions free of lattice artifacts.

Why were galaxies in the distant Universe so efficient at producing new stars? What were the roles of “nature” (stellar mass) and “nurture” (environment) in the past, how did they change with cosmic time and is there a connection between those and the declining star formation activity? Is our current view of how galaxies form and evolve correct? By probing a very wide range of environments (from fields to clusters of galaxies) and masses, we are now obtaining a much better picture of the roles and inter-dependences of mass and environment in the distant Universe. However, there are significant limitations in current studies, due to the small sample sizes, lack of multi-wavelenght data in cluster fields, projection effects, and the dilution/confusion of environments (e.g. filaments vs small groups). In order to obtain the sharp view that we need, overcoming current limitations (from the use of photometric redshifts), the student will start by using the VLT (with VIMOS [PI: D. Sobral], 40 hours of observations already conducted at the VLT, all in excellent conditions) to accurately map in 3-D a unique super-structure at z = 0.84 in the COSMOS field (10×13 Mpc). This massive, large structure contains 3 confirmed massive X-ray clusters/groups and shows a striking filamentary structure of star-forming galaxies. With >1000 galaxies residing in such structure, the student will measure accurate redshifts (from both emission and absorption lines) and make a detailed/accurate 3-D map of the complex structure, identifying filaments, fields, outskirts, small groups and the cluster cores. The student will obtain independent mass estimates from the absorption lines, and map SFRs down to even the least active galaxies, but also detect post-starburst galaxies (K+As) and map their fraction in the cluster, group, filament and field environments over the entire structure. The unique modelling capabilities developed at UL and UP, will be fully implemented to interpret and extract even more information from the high S/N, high quality spectra. The results of this project, coupled with a large field survey, will reveal exactly where star formation activity is being enhanced/quenched, clearly disentangling the roles of mass and environment in the distant Universe in a robust way for the first time.

Moreover, due to the fact that this super-structure is in the COSMOS field, the student will be able to fully explore the rich multi-wavelenght data-set to detail and expand the conclusions of the study (including with SED-modelling/fitting), particularly by investigating the morphologies (with Hubble Space Telescope imaging), but also to look at radio and far-infrared (Spitzer + Herschel) properties of galaxies residing in the various environments within the super-structure.

This project aims at significantly contributing towards one of the biggest unsolved questions/challenges in Astronomy/Astrophysics:

- Why were galaxies at the peak of the star formation history so much more active than typical galaxies now, and what are the main physical drivers of galaxy evolution?

http://www.nytimes.com/2012/11/20/science/space/births-of-stars-declining-sharply-astronomers-say.html?_r=0

http://newsfeed.time.com/2012/11/13/has-the-universe-almost-stopped-producing-new-stars/

The student will make significant contributions towards advancing our knowledge by extending the team's samples of star-forming galaxies across cosmic times (observations in Bootes, SA22, ELAIS N1 have been completed to add to the COSMOS and UDS catalogues already published by Sobral et al. 2012, 2013a) and fully exploring them with follow-up observations using new, powerful instruments. The thesis will allow the student to work and lead various sub-projects, to work on a truly international environment, and to observe on the best telescopes in the World (Mauna Kea - Hawaii; VLT and La Silla - Chile; WHT and INT - Canary Islands).

Pilot/first observations have already been conducted, yielding strong results. Taking advantage of the very significant amount of telescope time we have already been awarded (and will be applying for) as a PI (25 approved proposals on some of the most competitive facilities such as the 8-m Subaru or the ESO/VLT), but also as a Co-I (including ALMA time) and together with many collaborators in the USA, UK, Netherlands, Canada, Chile, Japan and Portugal, the student will be in an ideal position to explore the uniquely large samples of very distant galaxies (selected with the same method, over well-defined ages of the Universe) to understand exactly how/why galaxies like our own formed and how/why they have evolved in the way they did.

With new instrumentation/telescopes becoming available, the timing could not be better to explore the largest samples of star-forming galaxies and clearly pin-point what are the drivers of galaxy formation and evolution in the last 11 billion years of cosmic time.

Adaptive optics (AO) is an emerging domain where accurate photometry and astrometry is becoming a key challenge and promise. AO relies on the real time correction of atmospheric aberrations introduced in the wavefront. The classical concept is a wavefront sensor sensing a reference star and driving a deformable mirror. It delivers an optimal point spread function (PSF) towards the reference axis (on-axis) but it degrades away from the axis, a consequence of the reference only sampling the on-axis turbulence and of the de-correlation of turbulence for larger distances (angular anisoplanatism). Therefore the PSF is variable across the field-of-view. This is a strong limitation for the “classical” single conjugate adaptive optics as many astronomical applications require fields in excess of the few isoplanatic arcseconds. On the other hand this limitation is in a way similar to the much larger field (arcminutes) PSF variation observed in classical photometry.

The post-processing of adaptive optics data is a critical step in its astrophysical exploitation. Post-processing covers many aspects, mainly data deconvolution of individual extended objects and, most importantly in the context of the present project, photometric/astrometric extraction of stellar fields via PSF fitting codes. Most codes applied for photometric exploitation of AO fields are those available for standard non-AO photometry.

The challenges brought by adaptive optics and also by non-adaptive optics off-axis images are inevitable in the increasingly large focal planes and in the case of the European Extremely Large Telescope with ~40m segmented diameter as set forth in the ASTRONET roadmap and OPTICON technology programme. Addressing these challenges is the subject of this proposal.

Profile: Student with strong interest in astrophysics, optics/propagation, mathematical modelling, statistical physics, numerical simulations, data/signal processing. The work will accompany developments within the OPTICON framework and similar activities at LAM – Laboratoire d'Astrophysique de Marseille; availability of potential candidates to spend time in Marseille is required.

References:
Gilles, Correia et al, Simulation model based approach for long exposure atmospheric point spread function reconstruction for laser guide star multiconjugate adaptive optics, Applied Optics, vol. 51, issue 31, p. 7443 http://dx.doi.org/10.1364/AO.51.007443
Gilles, Correia et al, Tip/tilt point spread function reconstruction for laser guide star multi-conjugate adaptive optics, SPIE 2012, http://dx.doi.org/10.1117/12.926928

Astroparticle Physics	13	Astrophysics	27
Cosmology	6	Experimental Particle Physics	28
General Relativity	3	Theoretical Particle Physics	13

Thesis

Call: PhD Programme 2014

Contact point - LIP

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Thesis

Call: PhD Programme 2014

Contact point - LIP