Search for Lepton Flavor, Lepton Number, and Baryon Number Violating Tau Decay $\tau \rightarrow p \mu \mu$ at Belle

Abstract

Lepton flavor violation (LFV) is forbidden in the standard model. However, the observation of neutrino oscillations tells us that lepton flavor is not a good quantum number, implying LFV could also show up in the charged lepton sector. Baryon number violation (BNV) is believed to have occured in the early universe. BNV in charged lepton decays automatically implies both lepton number and lepton flavor violation. Any observation of BNV or LFV would be clear signal for beyond-the-standard-model physics. We present a search for the LFV and BNV decay channel $\tau \rightarrow p \mu \mu$ performed with the data recorded by the Belle experiment at the KEKB asymmetric-energy $e^+e^-$ collider.