A new evaluation of the hadronic vacuum polarisation contributions to the muon anomalous magnetic moment and to $\mathbf{\boldsymbol\alpha(m_Z^2)}$

TL;DR

This paper reevaluates the hadronic vacuum polarization contributions to the muon g-2 and the electromagnetic coupling at the Z boson mass, incorporating new data and addressing dataset discrepancies to refine theoretical predictions.

Contribution

It provides a new, more precise evaluation of hadronic contributions to muon g-2 and alpha(m_Z^2), including a detailed analysis of dataset discrepancies and their impact.

Findings

Muon (g-2)/2 contribution: (694.0 ± 4.0)×10^{-10}

Standard Model prediction differs from experiment by 3.3σ

Hadronic contribution to alpha(m_Z^2): (276.0 ± 1.0)×10^{-4}

Abstract

We reevaluate the hadronic vacuum polarisation contributions to the muon magnetic anomaly and to the running of the electromagnetic coupling constant at the $Z$-boson mass. We include newest $e^+e^- \to$ hadrons cross-section data together with a phenomenological fit of the threshold region in the evaluation of the dispersion integrals. The precision in the individual datasets cannot be fully exploited due to discrepancies that lead to additional systematic uncertainty in particular between BABAR and KLOE data in the dominant $\pi^+\pi^-$ channel. For the muon $(g-2)/2$, we find for the lowest-order hadronic contribution $(694.0 \pm 4.0)\cdot10^{-10}$. The full Standard Model prediction differs by $3.3\sigma$ from the experimental value. The five-quark hadronic contribution to $\alpha(m_Z^2)$ is evaluated to be $(276.0\pm1.0)\cdot10^{-4}$.