On the precision of a data-driven estimate of the pseudoscalar-pole contribution to hadronic light-by-light scattering in the muon g-2

TL;DR

This paper assesses the main momentum regions influencing the pseudoscalar-pole contribution to muon g-2 and evaluates how future form factor measurements can improve the data-driven estimate of this significant component.

Contribution

It identifies key momentum regions affecting the pseudoscalar-pole contribution and analyzes the impact of future form factor measurements on the estimate's precision.

Findings

Main contribution comes from specific photon momentum regions.

Future measurements can significantly reduce uncertainty in the estimate.

Provides guidance for experimental efforts to improve muon g-2 calculations.

Abstract

The evaluation of the numerically dominant pseudoscalar-pole contribution to hadronic light-by-light scattering in the muon g-2 involves the pseudoscalar-photon transition form factor F_{P gamma^* gamma^*}(-Q_1^2, -Q_2^2) with P = pi^0, eta, eta^\prime and, in general, two off-shell photons with spacelike momenta Q_{1,2}^2. We determine which regions of photon momenta give the main contribution for hadronic light-by-light scattering. Furthermore, we analyze how the precision of future measurements of the single- and double-virtual form factor impacts the precision of a data-driven estimate of this contribution to hadronic light-by-light scattering.