1. A window to the TeV scale and beyond from quark and lepton flavor physics
Yasuhiro Okada (KEK/Sokendai)
October 18, 2007
The 1st KPS-JPS joint session on particle physics, KPS meeting , Jeju, Korea

2. Role of flavor physics in the past
Flavor physics has provided basic inputs to formulate the particle physics model.
Absence of Lepton Flavor Violation in charged lepton decays
=> Two neutrino theory (Generation structure)
Suppression of Flavor Changing Neutral Current Processes
=> GIM mechanism (Charm quark)
CP violation in K decays
=> Kobayashi-Maskawa theory (Three generation structure)
“Basis of the Standard Model”

3. Critical time for particle physics
LHC experiment will start next year to explore the TeV physics.
TeV is the scale of the electroweak symmetry breaking, but most probably related to the “New Physics” scale.
New flavor experiments are under construction, (LHCb, BESSIII, MEG).
Future upgrade of the B factory is planned to improve capability of B, tau and charm physics.

4. Precision measurements
Precision measurements can provide indirect evidence of new physics or hints of physics at very high energy scales.
Impacts of LEP precision electroweak measurements
SUSY GUT?
A light Higgs boson?

5. The Unitarity triangle today
Although the CKM fit looks perfect, new physics contributions of several 10 % are still allowed.
Need more precision to be useful to explore the TeV physics.

6. Lepton Flavor Violation
No lepton flavor violation (LFV) in the Standard Model.
LFV in charged lepton
processes is negligibly small for a simple seesaw　neutrino model.
The MEG experiment will search for m ->e g up to level.
Y.Kuno and Y.O. 2001

7. Tau LFV Current bounds of tau LFV decays are 0(10-7) .
Relation between mu LFV and tau LFV depends on new physics models.
t ->eg upper bound
t ->mg upper bound
S.Banerjee, TAU 06

8. New physics examples
SUSY GUT and quark and lepton flavor signals (New physics in loops)
Charged Higgs interaction in B to tau decays
(New tree-level interaction)
Neutrino mass generation and LFV

9. SUSY and Flavor Physics
SUSY modes introduce SUSY partners.
Squark/sleption mass matrixes are new sources of flavor mixing and CP violation.
Super partners
SM particles
neutralino,
chargino
gluino
slepton
squark
W,Z,g, H
gluon
lepton
quark
Spin 1/2
Spin 0
Spin 1
Spin 1/2
Spin 1
Spin 1/2
Spin 0
Quark mass
Squark mass
SUSY breaking

10. SUSY breaking terms Quark flavor changing processes LHC/ILC
SUSY mass spectrum
Diagonal
Off-diagonal
Lepton flavor violation

11. SU(5) SUSY GUT with right-handed neutrinos
In the SUSY GUT case, the quark (neutrino) Yukawa coupling becomes
a source of LFV (quark FCNC).
Quark Yukawa coupling
Neutrino Yukawa coupling
GUT interactions
Quark flavor signals
Time-dep CP asymmetries in
B->fKs
B -> K*g
Bs->J/yf
Lepton flavor violation in
m->eg
t->mg
t->eg

12. Examples of flavor signals
Mixing-induced CP asymmetry:
S(B->K*g)
DS(fKs)=S(B->fKs)-S(B->J/yKs)
SuperB
SuperB
T.Goto, Y.O., T.Shindou and M.Tanaka, 2007

13. S(Bs->J/yf) LFV ( t ->mg, m->eg) t->mg LHCb m->eg
t->eg
T.Goto, Y.O., T.Shindou and M.Tanaka, 2007
Tau LFV and CPV in Bs mixing are correlated with Bd CPV signals.

14. Pattern of new physics signals in various SUSY models.
T.Goto, Y.O., T.Shindou and M.Tanaka, 2007
Promising signals
Possible deviations for some points
Pattern of deviations from the SM can provide a clue on physics determining
the structure of the SUSY breaking sector.

15. B to tau decays (B->tn, B->Dtn, B->D*tn)
New data from Belle and BABAR.
(Belle+BABAR)
(Belle)
(BABAR)
Sensitive to charged Higgs boson exchange diagrams.

16. Tauonic B decay The charged Higgs boson exchange diagram exists
in Two Higgs doublet model as well as SUSY models.
New contributions are important for the large tanb case b u t n W
B(B->tn)
Belle+BABAR H- b u t n
Charged Higgs exchange contribution
depends on

17. Correlation between B->tn and B->Dtn
MSSM with minimal flavor violation (MFV)
B(B->tn)
Belle+BABAR
B(B->Dtn)/B(B->Dmn)
Interesting to measure B->Dtn mode to resolve the twofold ambiguity.
H.Itoh, S.Komine, Y.O. 2005

18. Comparison with charged Higgs boson production at LHC
K.A.Assamagan, Y.Coadou, A.Deandrea　2002
B->Dtn 50ab-1
Sensitive to the same parameter space.
Test of “universality” of the charged Higgs couplings.
B->tn: H-b-u coupling
B->Dtn : H-b-c coupling
gb->tH: H-b-t coupling

19. Neutrino and LFV LFV is negligible for the simple seesaw model.
If some new ingredient is combined with the idea of the seesaw neutrino, LFV can be observable.
Tau processes have many modes whereas mu processes are more stringent in general.
and their CP conjugates
Present bounds 0(10-7)
Present bound

20. Left-right symmetric model
The LR symmetric model realizes a TeV scale seesaw mechanism.
LFV is induced by doubly charged Higgs bosons.
A example of tau and mu LFV processes
A.Akeroyd, M.Aoki, Y.O,2006

21. This is compared with the
SUSY GUT with seesaw
This is compared with the
SUSY seesaw model where SUSY loop diagrams gives dominant contributions.
t->mg
t->eg
Signals in different modes.
B(m->eg)
T.Goto, Y.O., T.Shindou and M.Tanaka, 2007

22. Summary
Quark flavor changing neutral current processes, rare decays and lepton flavor violation offer opportunities to search for new physics at the TeV scale in a different way from LHC.
If some new physics signals are observed, combinations of various signals can provide a hint for physics at higher scales.
In order for the flavor physics to be useful in the coming LHC era, the precision of various flavor measurements must be significantly improved, both in terms of experimental reach and understanding of theoretical uncertainty.