A study of the transition between quark gluon plasma and hadronic matter in an effective model of QCD: the Polyakov -- Nambu -- Jona-Lasinio model
type: Dataset
description: The quark and gluon plasma (QGP) is a state of matter observed in the collision of heavy ions in accelerators such as the LHC. It is formed at high temperature and / or high density, quarks are then deconfined : free to move and interacting very little with each other. At low temperature and low density, the quarks are, however, confined within hadrons forming the ordinary hadronic matter. The presence of the phase transition between hadronic matter and the QGP has observable consequences whatsoever at high temperature (RHIC and LHC experiments) or high density (FAIR experience, study of compact stars). A first phase transition is linked to the chiral symmetry breaking. In hadronic matter, this symmetry is spontaneously broken. It is restored by increasing the temperature or the density. Beyond the usual discussion on the chiral transition, we use a model called Polyakov Nambu Jona-Lasinio for describing a second transition, the deconfinement transition. This allows to separate the temperature-density diagram in three distinct phases : the hadronic phase where quarks are confined and where chiral symmetry is broken, the phase of the QGP where quarks are deconfined and chiral symmetry is restored and a hypothetical phase called quarkyonic at low temperature and high density in which quarks are confined but where chiral symmetry is still restored. We will describe, at first, the various transitions using the following order parameters : the quark condensate for the chiral transition and the Polyakov loop for the deconfinement one. Then we will see how the evolution of the spectral functions of sigma and pi mesons can provide information on the phase diagram. The chiral transition criterion will be the difference between the masses of these mesons, the mass being taken as the maximum of the spectral function. And the criterion for the deconfinement transition will be the standard deviation (also called variance) of the spectral function. Finally, we discuss how the vec…
issued: 2026-05-06T01:52:41.121314
language: fr
modified: 2026-05-06T01:52:41.121319
contact point: Organization
  fn: CCSD
keyword: boucle-de-polyakov
keyword: diagramme-de-phase-de-qcd
keyword: fonctions-spectrales
keyword: infoeu-reposemanticsdoctoralthesis
keyword: mesons
keyword: modele-njl
keyword: njl-model
keyword: phase-transition
keyword: physhexpphysics-physicshigh-energy-physics---experiment-hep-ex
keyword: plasma-de-quarks-et-de-gluons
keyword: polyakov-loop
keyword: qcd-phase-diagram
keyword: quark-and-gluon-plasma
keyword: spectral-functions
keyword: theses
keyword: transition-de-phase
landing page: https://theses.hal.science/tel-00958242

A study of the transition between quark gluon plasma and hadronic matter in an effective model of QCD: the Polyakov -- Nambu -- Jona-Lasinio model
type: Distribution
format: HTML
issued: 2026-05-06T01:52:41.154409
modified: 2026-05-06T01:52:41.103310
access URL: https://theses.hal.science/tel-00958242

test_moissonnage_selune
type: Agent