Lattice QCD calculation of hadronic light-by-light scattering

TL;DR

This paper presents a lattice QCD calculation of the hadronic light-by-light scattering amplitude, comparing results with phenomenological models and exploring the pion pole contribution, aiming to improve muon g-2 predictions.

Contribution

It introduces numerical methods for calculating the hadronic light-by-light contribution to muon g-2 using lattice QCD with two flavors and pion masses between 270 and 450 MeV.

Findings

Results agree with dispersive sum rule analysis at forward kinematics.

Pion pole contribution size is quantified for typical hadronic momenta.

Method demonstrates potential for precise muon g-2 calculations.

Abstract

We perform a lattice QCD calculation of the hadronic light-by-light scattering amplitude in a broad kinematical range. At forward kinematics, the results are compared to a phenomenological analysis based on dispersive sum rules for light-by-light scattering. The size of the pion pole contribution is investigated for momenta of typical hadronic size. The presented numerical methods can be used to compute the hadronic light-by-light contribution to the anomalous magnetic moment of the muon. Our calculations are carried out in two-flavor QCD with the pion mass in the range of 270 to 450MeV, and contain so far only the diagrams with fully connected quark lines.