Thesis

Quarks in a hot medium: propagators, confinement and chiral symmetry restoration

• Call:

  IDPASC Portugal - PHD Programme 2019

• Academic Year:

  2019 / 2020

• Domain:

  Theoretical Particle Physics

• Supervisor:

  Orlando Oliveira

• Co-Supervisor:

  Paulo Silva

• Institution:

  Universidade de Coimbra

• Host Institution:

  Universidade de Coimbra

• Abstract:

  Quantum Chromodynamics (QCD) describes the interactions between quarks and gluons. One of the puzzling properties of QCD being that its fundamental particles, i.e. quarks and gluons, are not observed in nature but appear as constituents of mesons and baryons. In strong interactions two of its main open questions are the understanding of confinement (why there aren’t free quarks and gluons) and the mechanism for the generation of mass scales that sets in for quarks and gluons and prevents infrared divergences. Current believe are that confinement and chiral symmetry breaking are interlaced. There are indications that for sufficiently high temperatures quarks and gluons behave essentially as a gas of free non-interacting particles, i.e. they seem to behave as deconfined particles. The formulation of QCD on a space-time lattice enables first principles determination of the quark and gluon propagators. From the propagators one accesses information about confinement/deconfinement and on the generation of mass scales, namely its running quark mass. The knowledge of the mass functions are crucial for the understanding of modern heavy ion experimental programs and for the history of the Universe. In this project we aim to compute, using the lattice QCD simulations, the quark propagator at finite temperature. Its main goal is to help understanding chiral symmetry breaking and the confinement/deconfinement properties of QCD as a function of the temperature by studying the properties of the various form factors that define the propagator and looking at its spectral representation. The knowledge of the spectral representation allows to investigate transport properties that are of paramount importance for the dynamical description of the heavy ion experimental programs. The simulations will be performed using the supercomputer facilities at the University of Coimbra. The candidate will join a team with a large experience in lattice QCD simulations.