Masato Yamanaka (ICRR, Univ. of Tokyo) Collaborators Masafumi Koike (Saitama Univ.) Yoshitaka Kuno (Osaka Univ.) Joe Sato (Saitama Univ. )  e ee

Introduction

In Standard Model (SM) Lepton Flavour Violation (LFV) through the neutrino oscillation But … Forever invisible Discovery of the LFV signal One of the evidence for beyond the SM

Introduction Prove for structure of new physics Comparing LFV signals in each process type Discrimination of new physics models Desire for detectable new LFV process Supersymetric model Extra dimension model

Introduction New idea for LFV search in muonic atom  e ee What is sensitive to ? Flavor violation between and e  Where is the stage ? MUSIC, COMET, and PRISM What is advantage ? Clean signal, and simultaneous search with other LFV processes

 e ee

 eee nucleus muon electron Muonic atom electron 1 S orbit muon 1 S orbit

 eee in muonic atom electron 1 S orbit muon 1 S orbit  e ee LFV vertex Interaction rate

 eee electron 1 S orbit muon 1 S orbit Interaction rate Cross section for elemental interaction in muonic atom  e ee LFV vertex

 eee Lagrangian LFV source Model dependent parmeters

 eee Lagrangian

 eee

 eee For A g (i = 1, 2, …, 6) L(R) = ～ i

 eee electron 1 S orbit muon 1 S orbit Interaction rate Overlap of wave function of and  e in muonic atom  e ee LFV vertex

 eee Muonic atom Overlap of wave functions ∴ Muon localizing at nucleus positon

 eee Branching ratio Lifetime of free muon ( s) -6 × Lifetime of bound muon s for H -6 × 1 (7 - 8) 10 s for U -8 × 238

Discovery reach

Branching ratio ( )  e  Ratio between BR( ) and BR( )  e   eee

Discovery reach Ratio between BR( ) and BR( )  e  eee ee

Discovery reach

For run-time 1 year 3 10 s × 7 ～ muon at COMET experiment

Discovery reach can be first signal of LFV !?  e ee

Summary

New LFV process in muonic atom  e ee Clean signal (back to back electron with E m /2) Interaction rate Advantage : Large nucleus ～ = e  Detectable in on-going or future experiments We wish to observe LFV in the process

Appendix

 eee nucleus muon electron Muonic atom electron 1 S orbit muon 1 S orbit

One of the candidates for beyond the SM Supersymmetric (SUSY) model Supersymmetry Lepton Slepton Gauge boson Gaugino Symmetry between boson and fermion Stability of Higgs mass, dark matter, gauge coupling unification, hierarchy problem, and so on Why SUSY models ??