Taming lattice artifacts with Pauli--Villars fields

TL;DR

Adding Pauli--Villars fields to lattice gauge theories helps reduce cutoff effects and gauge fluctuations, enabling simulations at stronger couplings and larger lattice spacings, which facilitates more controlled continuum extrapolations.

Contribution

The paper demonstrates that Pauli--Villars fields can mitigate lattice artifacts and extend the accessible physical region in lattice gauge theories with many light fermions.

Findings

Achieved larger renormalized couplings with reduced gauge fluctuations.

Damped short-distance fluctuations of the gauge field.

Enabled controlled continuum extrapolations from larger lattice spacings.

Abstract

As fermions are added to a lattice gauge theory, one is driven to stronger bare coupling in order to maintain the same renormalized coupling. Stronger bare couplings are usually associated with larger gauge fluctuations, leading to larger cutoff effects and more expensive simulations. In theories with many light fermions, sometimes the desired physical region cannot be reached before encountering a phase boundary. We show that these undesired effects can be reduced by adding Pauli--Villars fields. We reach significantly larger renormalized couplings while at the same time damping short-distance fluctuations of the gauge field. This may allow for controlled continuum extrapolations from large lattice spacings.