Thesis

Probing the primordial quark gluon plasma with heavy flavour

• Call:

  PT-CERN Call 2022/2

• Academic Year:

  2022

• Domain:

  Astroparticle Physics

• Supervisor:

  Nuno Leonardo

• Co-Supervisor:

  Yen-Jie Lee

• Institution:

  Instituto Superior Técnico (Universidade de Lisboa)

• Host Institution:

  Laboratório de Instrumentação e Física Experimental de Partículas

• Abstract:

  At the LHC, droplets of Quark Gluon Plasma (QGP) are created in Relativistic Heavy Ion Collisions. This exotic medium, named after its constituent particles, forms only under the uttermost conditions of temperature and baryon density. It is a state of quark matter predicted from Quantum Chromodynamics (QCD) as a consequence of the asymptotic freedom that colour charges manifest at high energies. As soon as the right conditions cease, this hot, dense, electrically and coloured-charged medium quickly harmonizes, giving rise to bound states like mesons and baryons. Nonetheless, exotic bound states like glueballs, tetra-quarks and so on are expected to form out of this rich environment. Hence, when a QGP droplet forms, it leaves a robust signature in particle detectors in terms of particle production, allowing its detailed study. All quark matter states can be sketched in the QCD phase diagram, which currently is still very unclear. Conducting QGP-related studies directly contributes to its mapping by examining the frontier where chiral symmetry breaks and hadronization takes place. Besides modern-day particle accelerators, QGP is associated only with extreme phenomena such as the vicinity of black holes, the core of neutron stars or even the quark epoch taking place right after the Big Bang. Thus, studies on the QGP are a window to the non-perturbative region of QCD but also to cosmology. A novel approach to studying the QGP is to explore heavy flavour states, now possible with the CMS detector at the LHC. More specifically, by exploring fully reconstructed b-hadrons, novel probes of the QGP that are achieved for the first time in nuclear collisions. This project aims at improving our understanding of quark hadronization, flavour and mass dependence of parton energy loss, and the underlying QCD mechanisms in the hot primordial medium.