Determination of Lee-Yang edge singularities in QCD by rational approximations
Kevin Zambello, D. Clarke, P. Dimopoulos, Francesco Di Renzo, Jishnu Goswami, Guido Nicotra, Christian Schmidt, Simran Singh
Abstract
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 $𝑁_\tau = 4, 6, 8$ lattices. The singularity structure of QCD in the complex $\mu_B$ plane is probed using conserved charges calculated at imaginary $\mu_B$. 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 $N_\tau = 6$ data with the $N_\tau = 4$ 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 $𝑁_\tau = 6, 8$ lattices.