Probing Lepton Flavor Violation at the ILC and CLIC

Abstract

Lepton flavor violation in the $\tau\mu$ sector would be a clear sign of Beyond Standard Model physics. We employ the SMEFT framework to study the process $e^+e^-\to\tau\mu$ at the ILC and CLIC. We find that the $e^+e^-$ beam polarizations achievable at these machines allow us to probe the chirality structure of the SMEFT operators. In addition, the high center of mass energy leads to a substantial increase in sensitivity to the four-fermion operators that rivals, and in some cases, surpasses tau decay projections from Belle-II.