The deconfinement transition of finite density QCD with heavy quarks from strong coupling series

TL;DR

This paper uses strong coupling series and Padé approximants to analyze the deconfinement transition in finite density QCD with heavy quarks, providing estimates for critical points and phase behavior.

Contribution

It introduces a novel application of strong coupling series and Padé analysis to determine critical couplings and phase transitions in lattice QCD with dynamical fermions.

Findings

Results agree with Monte-Carlo simulations for pure gauge theory.

Identified the second order critical point where the transition becomes a crossover.

Showed the shrinking of the first order region with increasing chemical potential.

Abstract

Starting from Wilson's action, we calculate strong coupling series for the Polyakov loop susceptibility in lattice gauge theories for various small N_\tau in the thermodynamic limit. Analysing the series with Pad\'e approximants, we estimate critical couplings and exponents for the deconfinement phase transition. For SU(2) pure gauge theory our results agree with those from Monte-Carlo simulations within errors, which for the coarser N_\tau=1,2 lattices are at the percent level. For QCD we include dynamical fermions via a hopping parameter expansion. On a N_\tau=1 lattice with N_f=1,2,3, we locate the second order critical point where the deconfinement transition turns into a crossover. We furthermore determine the behaviour of the critical parameters with finite chemical potential and find the first order region to shrink with growing \mu. Our series moreover correctly reflects the known Z(N) transition at imaginary chemical potential.