End point of the first-order phase transition of QCD in the heavy quark region by reweighting from quenched QCD

TL;DR

This study investigates the critical point of the first-order deconfinement phase transition in heavy quark QCD using reweighting from quenched simulations, revealing how the critical quark mass varies with lattice parameters.

Contribution

It introduces a reweighting approach with hopping parameter expansion to locate the critical point in heavy quark QCD on different lattice sizes and spacings.

Findings

Critical quark mass decreases with decreasing lattice spacing.

Critical quark mass increases with larger spatial volume.

Reweighting method's overlap problem is analyzed.

Abstract

We study the end point of the first-order deconfinement phase transition in two and 2+1 flavor QCD in the heavy quark region of the quark mass parameter space. We determine the location of critical point at which the first-order deconfinement phase transition changes to crossover, and calculate the pseudo-scalar meson mass at the critical point. Performing quenched QCD simulations on lattices with the temporal extents Nt=6 and 8, the effects of heavy quarks are determined using the reweighting method. We adopt the hopping parameter expansion to evaluate the quark determinants in the reweighting factor. We estimate the truncation error of the hopping parameter expansion by comparing the results of leading and next-to-leading order calculations, and study the lattice spacing dependence as well as the spatial volume dependence of the result for the critical point. The overlap problem of the reweighting method is also examined. Our results for Nt=4 and 6 suggest that the critical quark mass decreases as the lattice spacing decreases and increases as the spatial volume increases.