Speaker
Description
The muon anomaly, $𝑎_𝜇=\frac{(𝑔−2)}{2}$, is a low-energy observable which can be both measured and computed to high precision, making it a sensitive test of the Standard Model and a probe for new physics. The current discrepancy between the Standard Model calculation from the Muon $𝑔−2$ Theory Initiative [T. Aoyama et al. - Phys. Rept. 887 (2020), 1-166] and the experimental value is $𝑎^{\text{𝑆𝑀}}_𝜇−𝑎^{\text{𝑒𝑥𝑝}}_𝜇=(251±59)⋅10^{−11}$, with a significance of $4.2~𝜎$.
The anomaly was measured with a precision of 0.54 ppm by the Brookhaven E821 experiment and the E989 experiment at Fermilab aims for a four-fold improvement in precision, to confirm or refute the discrepancy. In Spring 2021, E989 published the first results of $𝑎_𝜇$ with a precision of 0.46 ppm using the data from the 2018 data-taking campaign. The measurement of the anomalous muon spin precession frequency, $𝜔_𝑎$, is based on the arrival time distribution of high-energy decay positrons observed by 24 electromagnetic calorimeters, placed around the inner circumference of a storage ring. This talk will present the analysis technique of $𝜔_𝑎$ and a preliminary status of the analysis performed on the datasets collected during Run 2 and 3 (2019 and 2020 campaigns).