Exploring Topology Conserving Gauge Actions for Lattice QCD

TL;DR

This paper investigates topology-conserving gauge actions in lattice QCD that suppress small plaquette values, enhancing topological stability and potentially improving simulations with dynamical quarks, demonstrated through numerical results.

Contribution

It introduces a class of gauge actions that strongly suppress small plaquettes, leading to increased topological stability and benefits for numerical lattice QCD studies.

Findings

Enhanced topological stability observed in simulations.

Favorable conditions for dynamical quark simulations.

Numerical results for static potential and overlap operator kernel.

Abstract

We explore gauge actions for lattice QCD, which are constructed such that the occurrence of small plaquette values is strongly suppressed. By choosing strong bare gauge couplings we arrive at values for the physical lattice spacings of O(0.1 fm). Such gauge actions tend to confine the Monte Carlo history to a single topological sector. This topological stability facilitates the collection of a large set of configurations in a specific sector, which is profitable for numerical studies in the epsilon-regime. The suppression of small plaquette values is also expected to be favourable for simulations with dynamical quarks. We use a local Hybrid Monte Carlo algorithm to simulate such actions, and we present numerical results for the static potential, the physical scale, the topological stability and the kernel condition number of the overlap Dirac operator. In addition we discuss the question of reflection positivity for a class of such gauge actions.