Hadronic light-by-light scattering contribution to the muon anomalous magnetic moment from lattice QCD

TL;DR

This paper presents a lattice QCD+QED calculation of the hadronic light-by-light scattering contribution to the muon anomalous magnetic moment, using non-perturbative methods and initial unphysical mass results to pave the way for a full physical-mass computation.

Contribution

It introduces a non-perturbative lattice QCD+QED approach to compute the hadronic light-by-light contribution to the muon g-2, including checks against perturbation theory.

Findings

Statistically significant signals obtained for unphysical masses.

Initial results are promising for future physical-mass calculations.

Discussion of prospects for complete, controlled-error computation.

Abstract

The form factor that yields the light-by-light scattering contribution to the muon anomalous magnetic moment is computed in lattice QCD+QED and QED. A non-perturbative treatment of QED is used and is checked against perturbation theory. The hadronic contribution is calculated for unphysical quark and muon masses, and only the diagram with a single quark loop is computed. Statistically significant signals are obtained. Initial results appear promising, and the prospect for a complete calculation with physical masses and controlled errors is discussed.