Massive photons: an infrared regularization scheme for lattice QCD+QED

TL;DR

The paper proposes a photon mass regularization scheme for lattice QCD+QED that simplifies infrared divergence removal, reducing computational costs while maintaining accuracy, especially for systems with multiple charged particles.

Contribution

Introducing a photon mass as an infrared regulator in lattice QCD+QED, enabling efficient and precise electromagnetic corrections without multiple volume extrapolations.

Findings

Electromagnetic corrections estimated with comparable precision to traditional methods.

Cost savings in ensemble generation for large-volume simulations.

Applicable to systems with multiple charged hadrons and long-range Coulomb interactions.

Abstract

Standard methods for including electromagnetic interactions in lattice quantum chromodynamics calculations result in power-law finite-volume corrections to physical quantities. Removing these by extrapolation requires costly computations at multiple volumes. We introduce a photon mass to alternatively regulate the infrared, and rely on effective field theory to remove its unphysical effects. Electromagnetic modifications to the hadron spectrum are reliably estimated with a precision and cost comparable to conventional approaches that utilize multiple larger volumes. A significant overall cost advantage emerges when accounting for ensemble generation. The proposed method may benefit lattice calculations involving multiple charged hadrons, as well as quantum many-body computations with long-range Coulomb interactions.