Measuring the muon's anomalous magnetic moment to 0.14 ppm

TL;DR

The paper reports a highly precise measurement of the muon's anomalous magnetic moment, revealing a persistent discrepancy with the Standard Model that suggests potential new physics beyond current theories.

Contribution

It presents an improved experimental measurement of the muon g-2 with 0.14 ppm precision and discusses theoretical and experimental advancements motivating future research.

Findings

Persistent 3.2 sigma discrepancy with Standard Model

Preparation for a new measurement at Fermilab with 0.14 ppm precision

Constraints on theories beyond the Standard Model

Abstract

The anomalous magnetic moment (g-2) of the muon was measured with a precision of 0.54 ppm in Experiment 821 at Brookhaven National Laboratory. A difference of 3.2 standard deviations between this experimental value and the prediction of the Standard Model has persisted since 2004; in spite of considerable experimental and theoretical effort, there is no consistent explanation for this difference. This comparison hints at physics beyond the Standard Model, but it also imposes strong constraints on those possibilities, which include supersymmetry and extra dimensions. The collaboration is preparing to relocate the experiment to Fermilab to continue towards a proposed precision of 0.14 ppm. This will require 20 times more recorded decays than in the previous measurement, with corresponding improvements in the systematic uncertainties. We describe the theoretical developments and the experimental upgrades that provide a compelling motivation for the new measurement.