LFV

1
LFV LNV in SUSY-2
Once R-parity is relaxed, LFV effects in SUSY can
be large
Current LFV data itself gives strictest limits on
the couplings. e.g. B(KL??e) lt 4.7 ? 10-12 gives
?i21?i12 and ?i12?i21 ? 6.2 ?
10-9(m?/100GeV)2 ?2i1?1i2 and ?1i1?2i2 ?
1.9 ? 10-7(m?/100GeV)2 SUSY can also give
like-sign lepton decays like K??-?e through b
mixing, e.g.


However the sensitivity for these is much
reduced. Even setting the b mixing
matrix Element to 1, current limit B(K??-?e)
lt 5 ? 10-10 would give ?2k2?11k ?
10(md/100GeV)2

k
2
LNV Majorana Neutrinos
Explanations of neutrino mixing tend to involve
Majorana neutrinos. These can mediate processes
like K??-? ? that violate LNV as well as LFV
Tends to be undetectably small, but theres a
possibility of resonant enhancement of the
left-hand diagram for heavy neutrinos in the mass
range 245-389 MeV. Present limit (from AGS-865)
is B(K??-? ? ) lt 3 ? 10-9 _at_ 90 CL. This
gives a constraint U?j2?(5.6?1) ?10-9 (see Dib
et al., hep-ph/0011213)
Appel et al. PRL 85 2877 (2000)
3
Prospects for LFV Experiments

• Last round of experiments pretty much killed the
  most promising theoretical predictions.
• Theorists now pointing at rare muon processes
• There are exceptions, e.g. Frère et al.
  hep-ph/0309014, large extra dimensions
• Future progress on LFV kaon decays likely to be
  slow
• No dedicated experiments on the horizon
• Background getting harder to fight

4
J-PARC Facility
J-PARC Japan Proton Accelerator Research Complex
5
J-PARC Accelerator complex

• Phase 1 Phase 2 189 billion Yen ( 1.89
  billion if 1 100 Yen).
• Phase 1 151 billion Yen for 7 years.
• Construction budget does not include salaries.

6
Construction Schedule
Phase 1 Completion
Construction Start
7
Proton accelerator in the world
8
Expected intensity of charged K beam

• Relatively larger increase for K- and K0 of
  higher momentum (?1 GeV).
• Factor 5-10 increase from BNL AGS intensities.
• Issues - duty factor, competition for protons
  (from ?)

9
T-violation in K?3

• Look for polarization asymmetry of ?
  polarization in K??0??
• Interference of SM and new physics magnifies
  effects (i.e. a 10-6 effect in the BR ? 10-3
  effect in this polarization)
• Particularly sensitive to multi-Higgs models,
  some SUSY, LQ, etc.

10
KEK-246 Detector
11
Muon Polarimeter
12
E246 Method
13
Progress in T-violation
PT -0.0018?0.023stat?0.0011syst (PT lt 0.0051
_at_ 90 C.L.) Im? -.0055?0.0073stat?0.0036syst (
Im? lt 0.016 _at_ 90 C.L.)
E246
In 3 HD Model, corresponds to neutron EDM lt
9?10-27 (cf 6.3?10-26)
14
K?3 Polarization at J-PARC
Goal measurement of PT in K?3 and in K???? to
10-4
15
90 CL upper limits on non-SM Decays
T-viol K?3
K???
16
90 CL upper limits on non-SM Decays
K???
17
K???
Violates angular momentum conservation, etc. Who
would even bother thinking about it?
B(K???) 8?10-17(1TeV/?NC)4 (hep-ph/0507231)
18
Summary of BSM Searches

• Dedicated experiments at BNL brought
  sensitivities in LFV processes to ?10-11.
• More or less wiped out the theories that
  motivated them
• MSSM tends to predict very small BRs
• Looking under the lampost
• New theoretical motivation developing slowing
• Further progress would require substantial
  investment
• Although 5-10? more incident protons available
• Developed techniques in beams and detectors that
  will be useful in K??ll
• Other BSM searches mainly by-products of
  experiments dedicated to other processes
• E.g. KTeV gets KL?????e e from KL???-ee- (not
  main object)
• The one exception is T-violating ? polarization
  in K?3 decay likely to be pursued at J-PARC