Hadron production within PHSD

TL;DR

This paper investigates hadron production in nucleus-nucleus collisions using the PHSD transport model extended to include chiral symmetry restoration, explaining the observed maximum in the $K^+/\pi^+$ ratio through combined CSR and deconfinement effects.

Contribution

The study introduces a microscopic approach combining CSR and deconfinement in PHSD to explain hadron production patterns in heavy-ion collisions.

Findings

CSR impacts strange to light quark production ratios.

Maximum in $K^+/\pi^+$ ratio explained by combined CSR and deconfinement.

Model reproduces experimental collision energy dependence.

Abstract

We study the production of hadrons in nucleus-nucleus collisions within the Parton-Hadron-String Dynamics (PHSD) transport approach that is extended to incorporate essentials aspects of chiral symmetry restoration (CSR) in the hadronic sector (via the Schwinger mechanism) on top of the deconfinement phase transition as implemented in PHSD. The essential impact of CSR is found in the Schwinger mechanism (for string decay) which fixes the ratio of strange to light quark production in the hadronic medium. Our studies provide a microscopic explanation for the maximum in the $K^+/\pi^+$ ratio at about 30 A GeV which only shows up if in addition to CSR a deconfinement transition to partonic degrees-of-freedom is incorporated in the reaction dynamics.