Connected and leading disconnected hadronic light-by-light contribution to the muon anomalous magnetic moment with physical pion mass

TL;DR

This paper presents a lattice QCD calculation of the hadronic light-by-light contribution to the muon g-2 at physical pion mass, including connected and leading disconnected diagrams, with preliminary results and ongoing error analysis.

Contribution

First lattice QCD calculation including both connected and leading disconnected diagrams for muon g-2 at physical pion mass with algorithmic improvements.

Findings

Calculated a_mu^{HLbL} = 5.35(1.35) x 10^{-10}

Includes connected and leading disconnected diagrams

Highlights ongoing work on finite-volume and disconnected contributions

Abstract

We report a lattice QCD calculation of the hadronic light-by-light contribution to the muon anomalous magnetic moment at physical pion mass. The calculation includes the connected diagrams and the leading, quark-line-disconnected diagrams. We incorporate algorithmic improvements developed in our previous work. The calculation was performed on the $48^3 \times 96$ ensemble generated with a physical-pion-mass and a 5.5 fm spatial extent by the RBC and UKQCD collaborations using the chiral, domain wall fermion (DWF) formulation. We find $a_\mu^{\text{HLbL}} = 5.35 (1.35) \times 10^{- 10}$, where the error is statistical only. The finite-volume and finite lattice-spacing errors could be quite large and are the subject of on-going research. The omitted disconnected graphs, while expected to give a correction of order 10\%, also need to be computed.