Mainz 2022 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 3: Heavy-Ion Collisions and QCD Phases II

HK 3.1: Gruppenbericht

Montag, 28. März 2022, 14:00–14:30, HK-H2

Kinetics of the chiral phase transition in a quark-meson σ model — •Hendrik van Hees, Carsten Greiner, and Alex Meistrenko — Institut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Str. 1, D-60438 Frankfurt am Main

A challenging goal in relativistic heavy-ion physics is the investigation of the phase diagram of strongly interacting matter and the determination of its phase structure, governed by the approximate chiral symmetry of the light-quark sector of QCD. In this study [1] we investigate a linear quark-meson σ model in and out of equilibrium employing Schwinger-Keldysh real-time techniques to derive a set of coupled Boltzmann-Uehling-Uhlenbeck (BUU) equations for the σ-mean field (the order parameter of the phase transition) and the quark- and meson phase-space distribution function from a Φ-derivable approximation. We numerically solve the equations to evaluate the grand-canonical baryon-number fluctuations for an expanding fireball. The evolution results in a temporary buildup of higher-order fluctuations of the net-baryon number like the curtosis at low momenta when the system is evolving close to the critical point or the first-order phase-transition line due to slowly evolving σ-mean field. This is partially counterballanced by the further dissipative evolution due to collisions of the quarks, mesons, and the mean field, leading to a considerable weakening of the final fluctuations, depending on the expansion rate of the fireball.

[1] Annals of Physics 431, 168555 (2021)