1. A like-sign dimuon charge asymmetry induced by the anomalous top quark couplings
이 강 영
(건국대학교)
@ 연세대학교, 서울

2. Based on J. P. Lee and KYL, arXiv:1010.6132.
J. P. Lee and KYL, Phys. Rev. D 78, (2008).
KYL and W. Y. Song, Phys. Rev. D 66, (2002).

3. Contents Introduction D0 like-sign dimuon charge asymmetry Constraints
Results
Top quark decays
Summary

4. Introduction
Like-sign dimuon charge asymmetry measured by D0 at Tevatron shows 3.2 σ deviation from the SM prediction.
More than top quarks will be produced at LHC in a year (at full power run).
Top quark couplings will be directly tested and nondiagonal couplings may be observed at LHC.
Anomalous top quark couplings are worth examining at present.

5. The CKM matrix Not directly measured >0.74 without unitarity
2008
Nobel prize awarded
Not directly measured
>0.74
without unitarity
D0 PRD78, (2008)
CDF Note 8968

6. Underlying new physics
Effective Lagrangian
Vtqeff : measures SM-like left-handed couplings
ξq : measures right-handed couplings
New particles, neutral current interactions are ignored.
Underlying new physics
Effective electroweak chiral Lagrangian
General Left-Right model (VLCKM≠VRCKM)
Etc.

7. D0 like-sign dimuon charge asymmetry
production at Tevatron
One muon comes from direct semileptonic decay :
The other muon comes from semileptonic decay
after neutral B meson mixing :

8. The dimuon charge asymmetry of semileptonic B decays is defined by
: Number of events of two b hadrons decaying into two muons with the charge of the same sign
comes from the asymmetry of the “wrong sign” semileptonic decays,
which are due to the oscillations of neutral Bd and Bs mesons.

9. Since both Bd and Bs mesons are produced at the Tevatron, is a linear combination of and .
Y. Grossman, Y. Nir, G. Raz, PRL 97, (2006)

10. - The Standard Model Predictions Non-zero
Difference between Bq and Bq decays
Mixing induced CP violation
A. Lenz, U. Nierste, JHEP 0706, 072 (2007)

11. D. Tsybychev, Talk given at the Johns Hopkins Workshop

12. measurements arXiv:1005.2757 [hep-ex] The measured value shows
deviations from the standard model prediction.
Previous measurement

13. Constraint I : B→Xsγ decays
ΔB=1 effective Hamiltonian
Oi : SM operators
Oi‘ : chiral conjugate operators
SM Wilson coefficients

14. Turn on the right-handed couplings
with the new loop functions

15. World average value of measurement
Branching ratio
A.L. Kagan, M. Neubert, EPJ, C7, 5 (1999)
M. Misiak and M. Steinhauser, NPB 764, 62 (2007)
M. Misiak et al., PRL 98, (2007).
SM prediction at NNLO
for
World average value of measurement
HFAG

16. Constraint II : Bq-Bq mixing
Schreodinger equation
Mass and width differences
Note that

17. Transition amplitude
with

18. SM predictions Measurements
A. Lenz and U. Nierste, JHEP 06, 072 (2007)
Measurements
HFAG
CDF, PRL 97, (2006)
D0, D0 note 5618-CONF

19. Results
B→Xsγ
B→Xsγ + Bs mixing
ξb =0
We obtain

20. ξs =0
We obtain

21. - - - No CP violation is predicted in Bs-Bs mixing in the SM.
(No phase in Vts and Vtb)
Combined analysis of current data of Bs-Bs mixing tells us that there exists some CP violation.
Our prediction of the phase of M12s is dominated by the phase of Vtseff.
The phase of Bd-Bd mixing is directly measured. - -

22. ξb =0
A. Lenz and U. Nierste, JHEP 06, 072 (2007)

23. Bs mixing
Bd mixing
sin 2β
ξs =0

24. Including dimuon charge asymmetry data
ξb =0
Including dimuon charge asymmetry data
B→Xsγ
B→Xsγ + Bs mixing
B→Xsγ + Bs mixing + Aslb

25. ξb =0

26. ξs =0 B→Xsγ B→Xsγ + Bs mixing B→Xsγ + Bs mixing + Bd mixing
B→Xsγ + Bs mixing + Bd mixing + Aslb

27. ξs =0

28. Wts
Wtb

30. Top quark decays Nondiagonal top quark decays
in the SM, but shifted in our approach,
which is insensitive to ξs and directly measure Vtseff .
Large deviation from the SM prediction is possible.

31. Note that in the SM
Including dimuon data
Can we measure it?

32. Summary
Impact of the anomalous right-handed top quark couplings on the like-sign dimuon charge asymmetry at Tevatron is studied in a model independent way.
Under the constraints from B→Xsγ decays and Bq-Bq mixing, the dimuon asymmetry can be explained.
Constraints on new physics parameters and predictions of departure from the SM are obtained.
Nondiagonal top quark decays might examine the tsW coupling directly and independently. -

33. Backup Slides

34. Preliminary Including dimuon charge asymmetry data ξb =0 B→Xsγ
B→Xsγ + Bs mixing
B→Xsγ + Bs mixing + Aslb
Preliminary

35. ξb =0
Preliminary