Parton dynamics and hadronization from the sQGP

TL;DR

This paper investigates the hadronization process of an expanding partonic fireball within the PHSD approach, showing how strong parton interactions and mean-field gradients influence collective flow and entropy production, aligning results with lattice QCD and statistical models.

Contribution

It introduces a dynamical model for parton hadronization that naturally accounts for entropy increase and reproduces experimental particle ratios at around 170 MeV.

Findings

Elliptic flow $v_2$ correlates linearly with spatial eccentricity $oldsymbol{ ext{epsilon}}$.

Hadronization via quark-antiquark fusion and three-quark recombination increases entropy.

Particle ratios match grandcanonical predictions at T ≈ 170 MeV.

Abstract

The hadronization of an expanding partonic fireball is studied within the Parton-Hadron-Strings Dynamics (PHSD) approach which is based on a dynamical quasiparticle model (DQPM) matched to reproduce lattice QCD results in thermodynamic equilibrium. Apart from strong parton interactions the expansion and development of collective flow is found to be driven by strong gradients in the parton mean-fields. An analysis of the elliptic flow $v_2$ demonstrates a linear correlation with the spatial eccentricity $\epsilon$ as in case of ideal hydrodynamics. The hadronization occurs by quark-antiquark fusion or 3 quark/3 antiquark recombination which is described by covariant transition rates. Since the dynamical quarks become very massive, the formed resonant 'pre-hadronic' color-dipole states ($q\bar{q}$ or $qqq$) are of high invariant mass, too, and sequentially decay to the groundstate meson and baryon octets increasing the total entropy. This solves the entropy problem in hadronization in a natural way. Hadronic particle ratios turn out to be in line with those from a grandcanonical partition function at temperature $T \approx 170$ MeV.