A New Measurement of the Muon Magnetic Anomaly

A new measurement of the positive muon's anomalous magnetic moment has been made at the Brookhaven Alternating Gradient Synchrotron using the direct injection of polarized muons into the superferric storage ring. The angular frequency difference omega_{a} between the angular spin precession frequency omega_{s} and the angular orbital frequency omega_{c} is measured as well as the free proton NMR frequency omega_{p}. These determine R = omega_{a} / omega_{p} = 3.707~201(19) ...

We present details on a new measurement of the muon magnetic anomaly, $a_\mu = (g_\mu -2)/2$. The result is based on positive muon data taken at Fermilab's Muon Campus during the 2019 and 2020 accelerator runs. The measurement uses $3.1$ GeV$/c$ polarized muons stored in a $7.1$-m-radius storage ring with a $1.45$ T uniform magnetic field. The value of $ a_{\mu}$ is determined from the measured difference between the muon spin precession frequency and its cyclotron frequency....

A higher precision measurement of the anomalous g value, a_mu = (g-2)/2, for the positive muon has been made at the Brookhaven Alternating Gradient Synchrotron, based on data collected in the year 2000. The result a_{mu^+} = 11 659 204(7)(5) times 10^{-10} (0.7 ppm) is in good agreement with previous measurements and has an error about one half that of the combined previous data. The present world average experimental value is a_mu(exp) = 11 659 203(8) times 10^{-10} (0.7 ppm...

The E821 experiment at Brookhaven National Laboratory is designed to measure the muon magnetic anomaly, a_mu, to an ultimate precision of 0.4 parts per million (ppm). Because theory can predict a_mu to 0.6 ppm, and ongoing efforts aim to reduce this uncertainty, the comparison represents an important and sensitive test of new physics. At the time of this Workshop, the reported experimental result from the 1999 running period achieved a_mu = 11 659 202(14)(6)x 10^-10 (1.3 ppm)...

QED, Hadronic, and Electroweak Standard Model contributions to the muon anomalous magnetic moment, a_mu = (g_mu-2)/2, are reviewed. Theoretical uncertainties in the prediction a_mu^SM = 116591597(67) times 10^{-11} are scrutinized. Effects due to ``New Physics'' are described. Implications of the current experiment vs. theory constraint a_mu^exp - a_mu^SM = 453(465) times 10^{-11} and anticipated near term error reduction to +- 155 times 10^{-11} are discussed.

The magnetic moment anomaly a_mu = (g_mu - 2) / 2 of the positive muon has been measured at the Brookhaven Alternating Gradient Synchrotron with an uncertainty of 0.7 ppm. The new result, based on data taken in 2000, agrees well with previous measurements. Standard Model evaluations currently differ from the experimental result by 1.6 to 3.0 standard deviations.

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 ...

This paper will cover the physics and methods behind Fermilab's Muon g-2 Experiment, along with the long-awaited results from Run-1. The experiment was undertaken to resolve the tension between the Standard Model and the previous measurement taken at Brookhaven National Laboratory. The measured value of the muon magnetic anomaly is $a_\mu(FNAL)=116592040(54)\times10^{-11}$. This result is in good agreement with Brookhaven's previous measurement. The new world average, $a_\mu(...

The muon (g-2) experiment at Brookhaven National Laboratory has measured the anomalous magnetic moment of the positive muon with a precision of 0.7 ppm. This paper presents that result, concentrating on some of the important experimental issues that arise in extracting the anomalous precession frequency from the data.

The Fermilab Muon $g-2$ experiment measures the muon anomalous magnetic moment with high precision. Together with recent improvements on the theory front, the first results of the experiment confirm the long-standing discrepancy between the experimental measurements and the Standard Model predictions. The observed value of $a_\mu({\rm FNAL}) = 116\,592\,040(54) \times 10^{-11} ~ (\text{0.46\,ppm})$, combined with the previous experimental measurement, results in a discrepancy...