The hadronic light-by-light contribution to the muon $g{-}2$ using staggered fermions at the physical point

TL;DR

This paper calculates the hadronic light-by-light contribution to the muon g-2 using lattice QCD with staggered fermions at the physical point, aiming to reduce theoretical uncertainties in the Standard Model prediction.

Contribution

It presents a direct lattice QCD evaluation of the hadronic light-by-light contribution at the physical point, including finite volume effects and pseudoscalar pole contributions.

Findings

Quantitative estimate of the hadronic light-by-light contribution

Assessment of finite volume effects on the calculation

Inclusion of pseudoscalar pole contributions using existing form factors

Abstract

Hadronic contributions dominate the uncertainty of the Standard Model prediction for the anomalous magnetic moment of the muon. In this work, we present results on the hadronic light-by-light contribution obtained from the evaluation of the hadronic four-point function of electromagnetic currents using the position-space formalism developed by the Mainz group. The simulations are performed with staggered fermions directly at the physical point. Several physical volumes are used to estimate finite volume effects. This direct lattice study is supplemented by considering the contribution of the light pseudoscalar pole in both finite and infinite volumes, where we reuse the pseudoscalar transition form factors that have been evaluated in previous simulations on the same ensembles.