Precise Measurement of the Positive Muon Anomalous Magnetic Moment

Abstract

A precise measurement of the anomalous $g$ value, ${a}_{\ensuremath{\mu}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}(g\ensuremath{-}2)/2$, for the positive muon has been made at the Brookhaven Alternating Gradient Synchrotron. The result ${a}_{{\ensuremath{\mu}}^{+}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}11659202(14)(6)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$ (1.3 ppm) is in good agreement with previous measurements and has an error one third that of the combined previous data. The current theoretical value from the standard model is ${a}_{\ensuremath{\mu}}(\mathrm{SM})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}11659159.6(6.7)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$ (0.57 ppm) and ${a}_{\ensuremath{\mu}}(\mathrm{exp}){\ensuremath{-}a}_{\ensuremath{\mu}}(\mathrm{SM})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}43(16)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$ in which ${a}_{\ensuremath{\mu}}(\mathrm{exp})$ is the world average experimental value.