The QCD crossover temperature and curvature coefficient from unbiased exponential resummation at physical quark masses in (2+1)-flavor lattice QCD
We present the first application of the unbiased exponential resummation method to the determination of the QCD pseudocritical temperature at vanishing baryon chemical potential . By reconstructing the finite-density baryon number susceptibility , we define two thermal-derivative observables whose peak positions yield MeV and MeV. We also show that the pseudocritical temperature, obtained from the peak of the fourth-order baryon number susceptibility is consistent with these determinations and with previous lattice-QCD results based on Taylor expansions \cite{Bollweg:2022Pade}. Further, we demonstrate that scaling relations \cite{Bollweg:2022fqq} between and the thermal derivatives of yield mutually consistent estimates of the leading second order curvature coefficient at the corresponding pseudocritical temperatures. A direct analysis of the dependence of the pseudocritical temperatures provides an independent but substantially less constrained determination of the curvature, which remains statistically consistent with the scaling-based estimates. These results demonstrate the consistency of unbiased exponential resummation with the expected scaling behavior and establish it as a complementary approach for probing the QCD crossover at small finite baryon density.