Two-flavor QCD correction to lepton magnetic moments at leading-order in the electromagnetic coupling

TL;DR

This paper provides a precise nonperturbative lattice QCD calculation of the leading-order two-flavor QCD correction to the anomalous magnetic moments of the electron, muon, and tau leptons, improving accuracy and control over systematic effects.

Contribution

It introduces a modified lattice QCD method that accurately includes disconnected diagrams and controls systematic uncertainties for lepton magnetic moment calculations.

Findings

Calculated QCD corrections: electron 1.513(43)×10^(-12), muon 5.72(16)×10^(-8), tau 2.650(54)×10^(-6).

Achieved better than 3% accuracy for all three leptons.

Controlled continuum, volume, and chiral limits in lattice calculations.

Abstract

We present a reliable nonperturbative calculation of the QCD correction, at leading order in the electromagnetic coupling, to the anomalous magnetic moment of the electron, muon, and tau leptons using two-flavor lattice QCD. We use multiple lattice spacings, multiple volumes, and a broad range of quark masses to control the continuum, infinite-volume, and chiral limits. We examine the impact of the commonly ignored disconnected diagrams and introduce a modification to the previously used method that results in a well-controlled lattice calculation. We obtain 1.513(43) 10^(-12), 5.72(16) 10^(-8), and 2.650(54) 10^(-6) for the leading-order two-flavor QCD correction to the anomalous magnetic moment of the electron, muon, and tau, respectively, each accurate to better than 3%.