Phase structure and critical point in heavy-quark QCD at finite temperature

TL;DR

This study investigates the phase structure and critical point of heavy-quark QCD at finite temperature using the hopping parameter expansion, confirming the universality class and developing methods for larger lattices.

Contribution

The paper introduces a new method to incorporate higher-order effects of the hopping parameter expansion for larger lattice sizes in heavy-quark QCD.

Findings

Critical scaling of Z(2) universality class confirmed for large aspect ratios.

LO and NLO approximations of HPE are accurate for N_t=4 and 6.

Developed a method to include higher-order HPE effects for larger N_t.

Abstract

We study phase structure and critical point of finite-temperature QCD in the heavy-quark region applying the hopping parameter expansion (HPE). We first study finite-size scaling on the critical point on $N_t=4$ lattices with large spatial volumes taking the leading order (LO) and the next-to-leading order (NLO) effects of the HPE, and find that the critical scaling of the Z(2) universality class expected around the critical point of two-flavor QCD is realized when the aspect ratio of the lattice is larger than about 9. This enables us to determine the critical point in the thermodynamic limit with high precisions. By a study of the convergence of the HPE, we confirm that the result of the critical point with the LO (NLO) approximation of the HPE is fairly accurate for $N_t=4$ (6), while we need to incorporate higher order effects for larger $N_t$. To extend the study to large $N_t$ lattices, we then develop a method to take the effects of higher-order terms of the HPE up to a sufficiently high order. We report on the status of our study on $N_t = 6$ lattice adopting the new method.