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

2. Introduction

3. 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

4. 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

5. 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

6.  e ee

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

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

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

10.  eee Lagrangian LFV source Model dependent parmeters

11.  eee Lagrangian

12.  eee

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

14.  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

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

16.  eee Branching ratio Lifetime of free muon (2.197 10 s) -6 × Lifetime of bound muon 2.19 10 s for H -6 × 1 (7 - 8) 10 s for U -8 × 238

17. Discovery reach

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

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

20. Discovery reach

21. For run-time 1 year 3 10 s × 7 ～ 10 18 10 19 -muon at COMET experiment

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

23. Summary

24. 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

25. Appendix

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

27. 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 ??