Hadronic light-by-light contribution to $(g-2)_\mu$: a dispersive approach

TL;DR

This paper discusses a dispersive approach to calculating the hadronic light-by-light contribution to the muon's anomalous magnetic moment, providing new estimates and outlining future prospects.

Contribution

It introduces a dispersive method for evaluating the hadronic light-by-light contribution, including numerical estimates for the pion box and rescattering effects.

Findings

Numerical estimate for the pion box contribution.

Assessment of rescattering corrections.

Outline of future dispersive calculation prospects.

Abstract

After a brief introduction on ongoing experimental and theoretical activities on $(g-2)_\mu$, we report on recent progress in approaching the calculation of the hadronic light-by-light contribution with dispersive methods. General properties of the four-point function of the electromagnetic current in QCD, its Lorentz decomposition and dispersive representation are discussed. On this basis a numerical estimate for the pion box contribution and its rescattering corrections is obtained. We conclude with an outlook for this approach to the calculation of hadronic light-by-light.