Status of the lepton g-2 and effects of hadronic corrections

TL;DR

This paper reviews the current status of the lepton g-2 measurements and theoretical predictions, emphasizing the hadronic contributions that are crucial for understanding potential signs of new physics.

Contribution

It provides an updated analysis of the hadronic effects on the muon g-2 and discusses the implications of existing discrepancies between experiment and Standard Model predictions.

Findings

Muon g-2 shows a 3-4 sigma deviation from SM predictions.

Hadronic corrections are the main source of theoretical uncertainty.

Precise measurements continue to test the foundations of quantum field theory.

Abstract

The electron and muon anomalous magnetic moments (AMM) are measured in experiments and studied in the Standard Model (SM) with the highest precision accessible in particle physics. The comparison of the measured quantity with the SM prediction for the electron AMM provides the best determination of the fine structure constant. The muon AMM is more sensitive to the appearance of New Physics effects and, at present, there appears to be a three- to four-standard deviation between the SM and experiment. The lepton AMMs are pure relativistic quantum correction effects and therefore test the foundations of relativistic quantum field theory in general, and of quantum electrodynamics (QED) and SM in particular, with highest sensitivity. Special attention is paid to the studies of the hadronic contributions to the muon AMM which constitute the main source of theoretical uncertainties of the SM.