A like-sign dimuon charge asymmetry induced by the anomalous top quark

couplings

이 강 영

( 건국대학교 )

LHC Workshop 2010 @ 건국대학교 , 서울 2010. 8. 10.-12.

Based on

J. P. Lee and KYL, in progressJ. P. Lee and KYL, arXiv:0809.0751. J. P. Lee and KYL, Phys. Rev. D 78, 056004 (2008).KYL and W. Y. Song, Phys. Rev. D 66, 057901 (2002).

Contents

• Introduction• D0 like-sign dimuon charge asymmetry • Constraints• Results• Top quark decays• Summary

Introduction• Like-sign dimuon charge asymmetry measured by D0 at Tevatron

shows 3.2 σ deviation from the SM prediction.

• More than 108-109 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.

The CKM matrix 2008 Nobel prize awarded

Not directly measured >0.74 without unitarity D0 PRD78, 012005 (2008)CDF Note 8968

Effective Lagrangian

Vtqeff : measures SM-like left-handed couplings

ξq : measures right-handed couplings

Underlying new physics• Effective electroweak chiral Lagrangian• General Left-Right model (VL

CKM≠VRCKM)

• Etc.

New particles, neutral current interactions are ignored.

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 :

Xb

XBB 00

bb

The dimuon charge asymmetry of semileptonic B decays is defined by

bb NN , : 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, bslA

which are due to the oscillations of neutral Bd and Bs mesons.

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, 151801 (2006)

The Standard Model Predictions

A. Lenz, U. Nierste, JHEP 0706, 072 (2007)

Non-zero Difference between Bq and Bq decaysMixing induced CP violation

-

D. Tsybychev, Talk given at the Johns Hopkins Workshop

measurements

The measured value shows deviations from the standard model prediction.

Previous measurement

arXiv:1005.2757 [hep-ex]

ΔB=1 effective Hamiltonian

Oi : SM operatorsOi‘ : chiral conjugate operators

SM Wilson coefficients

Constraint I : B→Xsγ decays

Turn on the right-handed couplings

with the new loop functions

Branching ratio

SM prediction at NNLOfor

M. Misiak and M. Steinhauser, NPB 764, 62 (2007)M. Misiak et al., PRL 98, 022002 (2007).

World average value of measurement HFAG

A.L. Kagan, M. Neubert, EPJ, C7, 5 (1999)

-

Mass and width differences

Schreodinger equation

Note that

Constraint II : Bq-Bq mixing

Transition amplitude

with

SM predictions A. Lenz and U. Nierste, JHEP 06, 072 (2007)

Measurements

HFAG

CDF, PRL 97, 242003 (2006)D0, D0 note 5618-CONF

We obtain

ξb =0

Results

B→Xsγ B→Xsγ + Bs mixing

We obtain

ξs =0

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.

-

-

-

ξb =0

A. Lenz and U. Nierste, JHEP 06, 072 (2007)

ξs =0

sin 2βBs mixing Bd mixing

Including dimuon charge asymmetry data

B→Xsγ B→Xsγ + Bs mixingB→Xsγ + Bs mixing + Asl

b

ξb =0

Preliminary

ξb =0

Preliminary

Top quark decays

Nondiagonal top quark decays

which is insensitive to ξs and directly measure Vtseff .

Large deviation from the SM prediction is possible.

in the SM, but shifted in our approach,

Note that in the SM

Can we measure it?

Including dimuon data

• 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.

Summary

-