On the phase structure of twisted mass lattice QCD

TL;DR

This paper investigates the phase structure of twisted mass lattice QCD using chiral perturbation theory, revealing extended phase scenarios and a potential new phase with discrete symmetry breaking, which is crucial for numerical simulations.

Contribution

It extends previous analyses of phase structures in twisted mass lattice QCD, identifying new phases and symmetry-breaking patterns relevant for simulations.

Findings

Identification of extended phase scenarios

Discovery of a possible new phase with Z2 symmetry breaking

Implications for numerical simulation stability

Abstract

The introduction of a chirally twisted mass term has been proposed as an attractive approach to O(a) improvement of Quantum Chromodynamics with Wilson fermions on a lattice. For numerical simulation projects it is important to know the phase structure of the theory in the region of small quark masses. We study this question in the framework of chiral perturbation theory. Generalizing the analysis of Sharpe and Singleton we find extensions of normal and Aoki phase scenarios and a possible new phase with spontaneous breakdown of chiral symmetry to a discrete $Z_2$.