Polyakov Loop Susceptibility and Correlators in the Chiral Limit

Abstract: In quenched QCD the Polyakov loop is an order parameter of the deconfinement transition, but with decreasing quark mass, the peak in the Polyakov loop susceptibility becomes less pronounced, and it loses its interpretation as an indicator for deconfinement. For this $N_f=2+1$ HISQ study, we fix the strange quark mass $m_s$ at its physical value and investigate the dependence of the Polyakov loop on the light quark mass $m_l$ in the range $m_s/m_l=27-160$, following $m_l$ toward the chiral limit. In particular we will look how the inflection point and susceptibility behave as we decrease $m_l$, to see whether one finds any indication of a crossover, and therefore whether the Polyakov loop is sensitive to the chiral phase transition. Preliminary results show no signal of a crossover from the real part of the Polyakov loop in the vicinity of the chiral crossover. Closely related is an investigation of Polyakov loop correlations and the Debye mass in this limit. Preliminary results suggest little or no dependence on $m_l$.