Conserved charge fluctuations with smaller-than-physical quark masses

TL;DR

This study investigates conserved charge fluctuations in 2+1 flavor QCD with lighter-than-physical quark masses, analyzing their dependence on quark mass and implications for the chiral phase transition.

Contribution

It provides new calculations of charge cumulants with lighter quark masses and explores the singular and regular parts, offering insights into the chiral transition behavior.

Findings

Quark mass dependence of up to 6th order cumulants analyzed

First results on separating singular and regular contributions

Insights into the chiral phase transition and crossover curvature

Abstract

We present results from calculations of conserved charge fluctuations in $(2+1)$-flavor QCD using light quark masses in the range $m_s/80 \leq m_l \leq m_s/27$, with the strange quark mass ($m_s$) kept fixed at its physical value. This corresponds to a Goldstone pion mass in the range $80$ MeV $\leq m_\pi \leq 140$ MeV. The measurements have been done using HISQ fermion discretization and Symanzik improved gauge action. We discuss the quark mass dependence of up to 6th order cumulants and present first results on the separation of singular and regular contributions to these cumulants. From these results, we examine the nature of the chiral phase transition and the variation of the curvature of the crossover line as we approach the chiral limit.