Vacuum Polarisation and Hadronic Contribution to muon g-2 from Lattice QCD

TL;DR

This study calculates the vacuum polarisation in lattice QCD to estimate the hadronic contribution to muon g-2, revealing agreement with perturbative QCD at high energies and non-perturbative effects at lower scales.

Contribution

It provides a lattice QCD computation of vacuum polarisation and estimates the light quark contribution to muon g-2, including analysis of non-perturbative effects and OPE applicability.

Findings

Results align with perturbative QCD above 2 GeV^2

Non-perturbative effects are observed below 2 GeV^2

Estimated light quark contribution to muon g-2 is 446(23) x 10^{-10}

Abstract

We compute the vacuum polarisation on the lattice in quenched QCD using non-perturbatively improved Wilson fermions. Above Q^2 of about 2 GeV^2 the results are very close to the predictions of perturbative QCD. Below this scale we see signs of non-perturbative effects which we can describe by the use of dispersion relations. We use our results to estimate the light quark contribution to the muon's anomalous magnetic moment. We find the result 446(23) x 10^{-10}, where the error only includes statistical uncertainties. Finally we make some comments on the applicability of the Operator Product Expansion to our data.