Description:

It is well established that quarks and neutral leptons (neutrinos) exhibit flavor violation. Observation of neutrino oscillation implies loop level charged lepton flavor violation (CLFV) at GIM suppressed rates of < 10−54, far beyond experimental reach. In the coming years three charged lepton flavor violating (CLFV) processes: μ → eγ , μ → eee and μN → eN will be explored at facilities around the world. Observation of CLFV in any of these experiments would be an unambiguous signal of physics beyond the Standard Model (BSM). This talk will detail the theoretical motivations behind these experiments, their current status, and their projected physics reaches. Specific emphasis will be given to the Mu2e experiment, based at Fermilab, which will search for the coherent, neutrino-less conversion of a negative muon into an electron in the field of an aluminum nucleus. Mu2e aims to improve upon the previous upper limit by four orders of magnitude and reach an unprecedented single event sensitivity of 3 × 10−17 on the conversion rate, indirectly probing effective mass scales up to 104 TeV/c2. Mu2e plans to start data-taking at the end of 2026. Looking further ahead, a discussion of how to interpret CLFV signals in these experiments will be presented, specifically focusing on elucidating a conversion signal. The practicalities of nuclear target choices will be explained with implications for the conversion searches at the proposed Mu2e-II experiment and Advanced Muon Facility.

Sophie Middleton, Senior Research Associate, Caltech

Host: Michael Schmitt