1. What is μ-e Conversion ? μ μ-+(A,Z)→e-+(A,Z) muon decay in orbit
Neutrino-less muon
nuclear capture
(=μ-e conversion)
1s state in a muonic atom
nucleus μ −
μ-+(A,Z)→e-+(A,Z)
τ=0.88μs for Al
Eμe ~ mμ-Bμ
Bμ: binding energy of the 1s muonic atom
muon decay in orbit
μ- →e-νν
nuclear muon capture
Γ(μ-N→νN’)
B(μ-N→e-N)=
μ-+(A,Z) →νμ+(A,Z-1)
Γ(μ-N→e-N)

2. Overview of the COMET Experiment
Proton Beam
pπμ
8GeV, ~7μA, 56kW
The Muon Source
Proton Target
Pion Capture
Muon Transport
The Detector
Muon Stopping Target
Electron Transport
Electron Detection
2x107 sec running
Single event sensitivity
2.6 x 10-17
Current best limit
7x10-13
using Au target
90% C.L. upper limit
6.0 x 10-17

3. , G. Macharasivili
, Y. Yudin
, T. Hayashi

4. Schedule
Engineering run in 2018