The muon's anomalous magnetic moment is now known with a precision of 0.19 ppm with the latest run-2 and run-3 results of the Fermilab g-2 experiment. Further improvement in the precision of the experimental result is expected in the near future as the analysis of the final, subsequent run's 4, 5 and 6 are underway. On the theoretical side, the largest source of uncertainty in the 0.37 ppm...
The Fermilab Muon g-2 Experiment measured the muon magnetic moment anomaly to a precision of 200 parts per billion (ppb), after combining data from 2019 and 2020 with those from 2018. It involves high-precision measurements of the anomalous muon spin precession frequency $\omega_a$, as well as the magnetic field experienced by the muons. $\omega_a$ is measured with polarized muons decaying in...
A dedicated measurement of additional radiation in $e^+e^- \to \mu^+\mu^-\gamma$ and $e^+e^- \to \pi^+\pi^-\gamma$ initial-state-radiation events is presented using the full $BABAR$ data sample. For the first time results are presented at next-to-leading and next-to-next-to-leading order, with one and two additional photons, respectively, for radiation from the initial and final states. The...
The MUon proton Scattering Experiment (MUSE) simultaneously measures elastic electron-proton and muon-proton scattering using the PiM1 beam line at Paul Scherrer Institute in Villigen, Switzerland. Using both positive and negative beam polarities, MUSE will extract the proton charge radius by scattering off a liquid hydrogen target and contribute precise data to the investigation of the proton...
The MUSE experiment at the Paul Scherrer Institute is measuring elastic lepton-proton scattering cross sections in a four-momentum transfer range from Q2 of approximately 0.002 to 0.08 GeV2 using positively and negatively charged electrons and muons. The extraction of the Born cross sections from the experimental data requires radiative corrections. Estimates of the instrumental uncertainties...