Measurement of the Positive Muon Anomalous Magnetic Moment to 127 ppb

Abstract

A new measurement of the magnetic anomaly $a_{\hat{I}}¼$ of the positive muon is presented based on data taken from 2020 to 2023 by the Muon $g-2$ Experiment at Fermi National Accelerator Laboratory (FNAL). This dataset contains over 2.5 times the total statistics of our previous results. From the ratio of the precession frequencies for muons and protons in our storage ring magnetic field, together with precisely known ratios of fundamental constants, we determine $a_{\hat{I}}¼=1165920710(162)\times 10^{-12}$ (139 ppb) for the new datasets, and $a_{\hat{I}}¼=1165920705(148)\times 10^{-12}$ (127 ppb) when combined with our previous results. The new experimental world average, dominated by the measurements at FNAL, is $a_{\hat{I}}¼(\text{exp})=1165920715(145)\times 10^{-12}$ (124 ppb). The measurements at FNAL have improved the precision on the world average by over a factor of four.

11 pages, 3 figures; 2 pages of supplement material