Hadronic Contribution to the muon $g-2$ factor

TL;DR

This paper refines the theoretical calculation of the muon's anomalous magnetic moment by using operator product expansion and QCD sum rules, reducing the discrepancy with experimental measurements.

Contribution

It introduces a novel QCD finite energy sum rule approach that minimizes reliance on $e^+ e^-$ data, improving the agreement between theory and experiment.

Findings

Discrepancy between experiment and theory reduced from 28.7 to 19.2 in units of 10^{-10}

Method maintains the same uncertainty while improving accuracy

Supports the validity of QCD-based approaches in precision muon g-2 calculations

Abstract

The lowest order hadronic contribution to the $g-2$ factor of the muon is analyzed in the framework of the operator product expansion at short distances, and a QCD finite energy sum rule designed to quench the role of the $e^+ e^-$ data. This procedure reduces the discrepancy between experiment and theory, $\Delta a_\mu \equiv a^{EXP}_\mu - a^{SM}_\mu$, from $\Delta a_\mu = 28.7 (8.0) \times 10^{-10}$ to $\Delta a_\mu = 19.2 (8.0) \times 10^{-10}$, i.e. without changing the uncertainty.