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.
Highlights
Quantum chromodynamics (QCD) is known to have a rich phase structure as a function of temperature T, quark chemical potential μ, and quark masses mq
We study the end point of the first-order deconfinement phase transition in two- and 2 þ 1-flavor QCD in the heavy quark region of the quark mass parameter space
From quenched QCD simulations combined with the hopping parameter expansion, we found that the first-order deconfinement transition in the heavy quark limit becomes weaker and eventually disappears as the quark mass decreases
Summary
Quantum chromodynamics (QCD) is known to have a rich phase structure as a function of temperature T, quark chemical potential μ, and quark masses mq. We study the end point of the first-order deconfinement transition in the heavy quark region of twoand 2 þ 1-flavor QCD, and evaluate the critical quark mass at the end point. From quenched QCD simulations combined with the hopping parameter expansion, we found that the first-order deconfinement transition in the heavy quark limit becomes weaker and eventually disappears as the quark mass decreases. We determined the location of the critical surface separating the first-order and crossover regions around the heavy quark limit. We extend these studies using finer lattices with temporal lattice sizes Nt 1⁄4 6 and 8, and compare the results with those at Nt 1⁄4 4 to discuss the lattice spacing dependence of the critical point. In the Appendix, we introduce the multipoint histogram method used in this study
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