Theoretical status of the muon g-2

TL;DR

This paper reviews the current theoretical understanding of the muon g-2 within the Standard Model, focusing on hadronic contributions and uncertainties, and discusses the implications of discrepancies with experimental data.

Contribution

It provides a comprehensive review of recent calculations of hadronic effects and highlights the uncertainties and potential improvements in the theoretical evaluation of muon g-2.

Findings

Uncertainties in hadronic vacuum polarization affect the muon g-2 calculation.

Discrepancies exist between e+e- and tau data in hadronic contributions.

No definitive conclusion on new physics due to current data inconsistencies.

Abstract

We review the present status of the theoretical evaluation of the anomalous magnetic moment of the the muon within the Standard Model. We mainly focus on the hadronic contributions in the muon g-2 due to vacuum polarization effects, light-by-light scattering and higher order electroweak corrections. We discuss some recent calculations together with their uncertainties and limitations and point out possible improvements in the future. In view of the inconsistent values for the hadronic vacuum polarization based on e^+ e^- and tau data, no conclusion can be drawn yet, whether the apparent discrepancy between the current experimental and theoretical values for the muon g-2 points to physics beyond the Standard Model.