Evaluation of the three-flavor quark-disconnected contribution to the muon anomalous magnetic moment from experimental data

TL;DR

This paper provides a data-driven determination of the three-flavor quark-disconnected contribution to the muon anomalous magnetic moment, serving as a benchmark for lattice QCD calculations and improving understanding of hadronic effects.

Contribution

It introduces a physical observable for the combined strange-quark-connected and disconnected contributions and offers a data-based estimate in the isospin limit, facilitating comparison with lattice results.

Findings

Data-based value of $a_\mu^{\mathrm{LO,HVP}}$ in the isospin limit

Determination of the disconnected contribution as approximately -13 to -15×10^{-10}

Results serve as targets for lattice QCD validation

Abstract

We point out that the sum of the strange-quark-connected and full, three-flavor quark-disconnected contributions to the leading-order hadronic vacuum polarization contribution, $a_\mu^{\mathrm{LO,HVP}}$, to the anomalous magnetic moment of the muon, is a physical observable, and provide a data-based determination of this quantity in the isospin limit. The result, $40.1(1.5)\times 10^{-10}$, or $38.7(2.0)\times 10^{-10}$, depending on which data compilation is used, serves as a target of comparison for lattice calculations of the same isospin-limit combination. Subtracting from this result the average of lattice determinations of the strange-quark-connected contribution, one obtains also an alternate determination of the isospin-limit three-flavor disconnected contribution to $a_\mu^{\mathrm{LO,HVP}}$. The result of this determination, $-13.3(1.5)\times 10^{-10}$, or $-14.6(2.0)\times 10^{-10}$, depending on which data compilation is used, agrees well and is competitive with the most precise current lattice determination.