QCD phase diagram for finite imaginary chemical potential with HISQ fermions

Abstract

We present results from an ongoing study of the phase diagram of (2+1)-flavor QCD using the HISQ action with smaller than physical light quark masses in the Roberge-Weiss (RW) plane on lattices with temporal extent $N_{\tau }=4$. We find that the endpoint of the $1^{st}$ order RW transition line remains $2^{nd}$ order at least down to light quark masses corresponding to Goldstone pion masses of $55$ MeV. Furthermore, we show that the chiral condensate is sensitive to the RW transition and may serve as a energy-like operator characterizing universal behavior close to the RW endpoint.

Comments: 7pages, 11 figures, Prepared for the proceedings of LATTICE2018, held at Michigan State University, East Lansing, Michigan, USA