# Chiral phase structure of three flavor QCD at vanishing baryon number density

## TL;DR

This study explores the phase structure of three-flavor QCD at zero baryon density using lattice simulations, estimating an upper bound for the critical pion mass where a first-order phase transition may occur.

## Contribution

It provides the first lattice-based estimate of the critical pion mass for the chiral phase transition in three-flavor QCD at zero baryon density.

## Key findings

- No evidence of first-order transition for pion masses between 80 and 230 MeV.
- Estimated upper bound for critical pion mass is approximately 50 MeV.
- Chiral observables follow universal scaling near the critical point.

## Abstract

We investigate the phase structure of QCD with 3 degenerate quark flavors as function of the degenerate quark masses at vanishing baryon number density. We use the Highly Improved Staggered Quarks on lattices with temporal extent $N_{t}=6$ and perform calculations for six values of quark masses, which in the continuum limit correspond to pion masses in the range $80~{\rm MeV} \lesssim m_{\pi} \lesssim 230~$MeV. By analyzing the volume and temperature dependence of the chiral condensate and chiral susceptibility we find no direct evidence for a first order phase transition in this range of pion mass values. Relying on the universal scaling behaviors of the chiral observables near an anticipated chiral critical point, we estimate an upper bound for the critical pion mass, $m_\pi^c \lesssim$ 50 MeV, below which a region of first order chiral phase transition is favored.