Mass sensitivity of the three-flavor chiral phase transition

TL;DR

This study investigates how the mass of quarks influences the nature of the chiral phase transition in QCD, considering axial symmetry effects, using a low-energy quark-meson model with non-perturbative quantum fluctuations.

Contribution

It introduces a detailed analysis of mass sensitivity in the chiral transition using a functional renormalization group approach with a heuristic parameter fixing scheme.

Findings

Vacuum and thermal fluctuations significantly affect the transition order.

Parameter fixing ambiguities impact the spontaneous chiral symmetry breaking.

The model provides insights into the phase structure of QCD at low energies.

Abstract

The mass sensitivity of the chiral phase transition of QCD with and without axial $U_A(1)$-symmetry breaking at vanishing and finite quark chemical potential is investigated. To focus on the low-energy sector of QCD, a quark-meson model with three dynamical quark flavors is employed. Non-perturbative quantum fluctuations are taken into account with the functional renormalization group. The inherent ambiguities in fixing the low-energy model parameters away from the physical mass point and their consequences for spontaneous chiral symmetry breaking are discussed in detail and a heuristic parameter fixing scheme motivated by chiral perturbation theory is proposed. The influence of vacuum and thermal fluctuations of quarks and mesons on the order of the chiral phase transition is additionally assessed with a mean-field analysis.