QCD phase diagram with 2-flavor lattice fermion formulations

TL;DR

This paper introduces a new lattice QCD framework using Karsten-Wilczek fermions to study the phase diagram at finite temperature and density, maintaining chiral symmetry and reducing species number.

Contribution

The study demonstrates the applicability of Karsten-Wilczek fermions in finite-($T$,$ ho$) QCD, deriving an effective potential and critical line consistent with expected phase behavior.

Findings

Critical line of chiral phase transition derived

Effective potential of scalar meson obtained

Renormalization of imaginary chemical potential controlled

Abstract

We propose a new framework for investigating two-flavor lattice QCD with finite temperature and density. We consider the Karsten-Wilczek fermion formulation, in which a species-dependent imaginary chemical potential term can reduce the number of species to two without losing chiral symmetry. This lattice discretization is useful for study on finite-($T$,$\mu$) QCD since its discrete symmetries are appropriate for the case. To show its applicability, we study strong-coupling lattice QCD with temperature and chemical potential. We derive the effective potential of the scalar meson field and obtain a critical line of the chiral phase transition, which is qualitatively consistent with the phenomenologically expected phase diagram. We also discuss that $O(1/a)$ renormalization of imaginary chemical potential can be controlled by adjusting a parameter of a dimension-3 counterterm.