Phase structure of thermal lattice QCD with N_f=2 twisted mass Wilson fermions

TL;DR

This paper maps the phase diagram of lattice QCD with twisted mass Wilson fermions at finite temperature, revealing the existence of an Aoki phase, the Sharpe-Singleton scenario, and the shape of the thermal transition surface.

Contribution

It provides the first comprehensive numerical analysis of the phase structure of twisted mass Wilson fermions at finite temperature across a wide parameter space.

Findings

Confirmed the Aoki phase at strong coupling.

Observed the Sharpe-Singleton scenario at intermediate couplings.

Identified the cone-shaped phase boundary for the thermal transition.

Abstract

We present numerical results for the phase diagram of lattice QCD at finite temperature in the formulation with twisted mass Wilson fermions and a tree-level Symanzik-improved gauge action. Our simulations are performed on lattices with temporal extent N_\tau=8, and lattice coupling \beta ranging from strong coupling to the scaling domain. Covering a wide range in the space spanned by the lattice coupling \beta and the hopping and twisted mass parameters \kappa and \mu, respectively, we obtain a comprehensive picture of the rich phase structure of the lattice theory. In particular, we verify the existence of an Aoki phase in the strong coupling region and the realisation of the Sharpe-Singleton scenario at intermediate couplings. In the weak coupling region we identify the phase boundary for the physical finite temperature phase transition/crossover. Its shape in the three-dimensional parameter space is consistent with Creutz's conjecture of a cone-shaped thermal transition surface.