Lepton flavor violation at $\mu$TRISTAN and beyond

by Kare Fridell

Thursday 1 Jun 2023, 16:00 → 17:00 Australia/Sydney

Violation of charged lepton flavor is a clear sign of New Physics beyond the Standard Model. It is also potentially connected to neutrino Majorana masses as well as the generation of a matter/antimatter asymmetry of the Universe via leptogenesis. In order to probe such scenarios we study charged lepton flavor violating processes $\mu^+\mu^+\to\ell^+\ell'^+$ at the proposed same-sign muon collider $\mu$TRISTAN. Using effective field theory, we compare the discovery reach with existing limits from rare $\mu$ and $\tau$ decays, finding that $\mu$TRISTAN would be the most sensitive probe of charged lepton flavor violation for a range of parameters. As a model example, we then consider the type-ii seesaw model, and show how $\mu$TRISTAN could be used to constrain the CP-violating phases of the corresponding PMNS matrix.