Determination of Lee-Yang edge singularities in QCD by rational approximations

We report updated results on the determination of Lee-Yang edge (LYE) singularities in N_f = 2+1 QCD using highly improved staggered quarks (HISQ) with physical masses on N_τ = 4, 6, 8 lattices. The singularity structure of QCD in the complex μ_B plane is probed using conserved charges calculated at imaginary μ_B. The location of the singularities is determined by studying the (uncancelled) poles of multi-point Padé approximants. We show that close to the Roberge-Weiss (RW) transition, the location of the LYE singularities scales according to the 3-d Z(2) universality class. By combining the new N_τ = 6 data with the N_τ = 4 data from our previous analysis we extract a rough estimate for the RW temperature in the continuum limit. We also discuss some preliminary results for the singularities close to the chiral phase transition obtained from simulations on N_τ = 6, 8 lattices.