Estimates of Lee-Yang zeros and critical point for finite isospin densities in (2+1)-flavor lattice QCD using unbiased exponential resummation

Abstract: Estimated using the unbiased exponential resummation formalism on (2+1)-flavor QCD with physical quark masses on $\Nt=8$ lattice, we present the first calculations of Lee-Yang zeros of QCD partition function in complex isospin chemical potential $\muI$ plane. From these zeros, we obtain the resummed estimate of radius of convergence, which we compare with the corresponding ratio and Mercer-Roberts estimates of the subsequent Taylor series expansions of the first three cumulants. We also illustrate a comparative study between the resummed and the Taylor series results of different partition function cumulants for real and imaginary values of $\muI$, discussing the behaviour of different expansion orders within and beyond the so-obtained resummed estimate of radius of convergence. We show that the reweighting factor and phasefactor begin to attain zero from this resummed estimate of radius of convergence. In this paper, we crosscheck this resummation methodology in baryochemical potential $\muB$ and affirm its validity in finite statistics limit. We also briefly compare this method with Taylor and \pade resummation results in $\muB$. We also re-establish this resummed radius of convergence can capture the onset of overlap problem for finite real $\muI$ simulations.