中国物理学会高能物理分会第十三届全国粒子物理学术会议（2021）

In the Standard Model, Flavor-changing-neutral-current (FCNC) in quark sector is predicted at loop level. In the lepton sector, the lepton-flavor-violation (LFV) was evident after the discovery of neutrino oscillation. In the SM, even considering the tiny masses and oscillation of neutrinos, the predicted decay rate for charged-lepton-flavor-violation (cLFV), such as muon-electron conversion, is still tiny (less than 10^-54), which can not be detected in experiment. However, New Physics contributions can enhance the muon-electron conversion rate, and lead to observable signal. The COMET experiment and Mu2e experiment are proposed to search for the muon-electron conversion with the sensitivity improved by the order of 4 magnitudes comparing to the current upper limit. Any experimental evidence of cLFV will indicate signal of New Physics.