## Séminaire de Physique Théorique

**Finite temperature Dirac field under rotation**

Victor Ambruş (Université de l'Ouest, Timișoara, Roumanie)

jeudi 14 novembre 2019 14:00 - Tours - Salle 1180 (Bât E2)

**Résumé :**

Relativistic heavy ion collision experiments show that at sufficiently large centre-of-mass energy, a deconfined state of quarks and gluons, called the quark gluon plasma (QGP), is formed. The temperature of the QGP exceeds 130 MeV (1.5x10^{12} K), being of the order of magnitude of the temperature of the Universe a few microseconds after the Big Bang. Its equivalent mass density is of the order of 6x10^{18} kg/m^3, being denser than an atomic nucleus or the core of a neutron star. In non-central collisions, the vorticity of the resulting fluid can exceed 10^{22} s^{-1}. All these features make the QGP the hottest, densest and most vortical form of matter ever created in the laboratory [1]. Recent experimental data suggest that the Lambda hyperons formed in relativistic heavy ion collisions are polarized [1]. This polarization can be explained, e.g., via the chiral vortical effect [2], using quantum field theory at finite temperature. This talk reviews some analytical and numerical techniques that can be employed to compute the thermal expectation values of the charge current (CC), axial current (AC) and stress-energy tensor (SET) corresponding to the free Dirac field for a rigidly-rotating thermal state [3] at finite chemical potential [4]. The results are compared to the predictions of the relativistic kinetic theory (RKT) and the properties of quantum corrections are discussed, highlighting the regime where they become dominant [5]. The second part of the seminar is focussed on the properties of rotating states inside a cylinder, which is placed inside the speed of light surface. The thermal states are constructed using various boundary conditions, such as the MIT bag model [6]. References: [1] STAR collaboration, Nature 548 (2017) 62. [2] D. E. Kharzeev, J. Liao, S. A. Voloshin, G. Wang, Prog. Part. Nucl. Phys. 88 (2016) 1. [3] V. E. Ambruș, E. Winstanley, Phys. Lett. B 734 (2014) 296. [4] V. E. Ambruș, E. Winstanley, arXiv:1908.10244 [hep-th]. [5] V. E. Ambruș, Phys. Lett. B 771 (2017) 151. [6] V. E. Ambruș, E. Winstanley, Phys. Rev. D 93 (2016) 104014.

**Liens :**