Brillouin improvement for Wilson fermions

TL;DR

This paper introduces a new Wilson-type lattice Dirac operator with an extensive stencil to reduce rotational symmetry breaking, demonstrating improved scaling and localization in quenched QCD applications.

Contribution

It presents a parameter-free, 81-point stencil Wilson-type operator that enhances rotational symmetry and localization, with practical benefits in lattice QCD computations.

Findings

Improved scaling of pseudoscalar decay constants in quenched QCD.

The new operator is cheaper to construct and more localized as an overlap kernel.

Effective in the physical charm quark region.

Abstract

We present a parameter-free Wilson-type lattice Dirac operator with an 81-point stencil for the covariant derivative and the Laplacian which attempts to minimize the breaking of rotational symmetry near the boundary of the Brillouin zone. The usefulness of this "Brillouin operator" in practical applications is explored by studying the scaling of pseudoscalar decay constants in quenched QCD, with rather good results in the physical charm region. We also investigate the suitability of this operator as a kernel to the overlap procedure. Here, the resulting overlap operator is found to be cheaper to construct and significantly better localized than the variety with the standard Wilson kernel.