t violation in baryonic b decays
DESCRIPTION
Chao-Qiang Geng ( 耿朝強 ) National Tsing Hua University (Taiwan) ( Int. Conf. on QCD and Hadronic Physics , Beijing, June. 16-20, 2005). T Violation in Baryonic B Decays. Outline. 1. Motivation. 2. T-odd triple product correlations. 3. T violating effects in baryonic B decays. 4. Summary. - PowerPoint PPT PresentationTRANSCRIPT
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Chao-Qiang Geng ( 耿朝強)National Tsing Hua University (Taiwan)
(Int. Conf. on QCD and Hadronic Physics, Beijing, June. 16-20, 2005)
T Violation in Baryonic B Decays
Outline
1. Motivation
2. T-odd triple product correlations
3. T violating effects in baryonic B decays
4. Summary
● The work was done with Dr. Y.K. Hsiao.
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1. Motivation:
CP violation K system: indirect (ε) and direct (L)
B system: mixed induced (BJ/s)+ direct (BK)
T violation K system: indirect (ε)
B system: ?
CPT Theorem: CP violation ⇔ T violation
● To look for direct T violating effects in B system in the standard model
Goal: → To test the SM and find out New Physics
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→
☺Three-body charmless baryonic B decays:
● Rich spin and momentum structures: many T-odd correlations can be constructed!
● Measurable Λ polarization: Λ→pπ
● T violating effects in the SM are accessible at the current B-factories!
● Large BRs: Br(B→BB’P) >> Br(B→BB’)
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2. T-odd triple product correlations (TPCs)
T-odd asymmetry
TPC asymmetry with the conjugate process
Weak Strong phase
δ=0 → ≠ 0 (maximal)
Unlike the direct CP asymmetry: → 0 if δ=0
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3. T violating effects in baryonic B decays
Using the generalized factorization method:
C. Q. G.+Y.K. Hsiao
Chua, Hou,Tsai, PRD66 (2002) 054004.Chua,Hou, Eur. Phys. J. C 29 (2003) 27..
(see D.S.Du’s talk)
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Four components of Λ spin:Three polarization directions:
The longitudinal, normal and transverse Λ polarizations:
The Integrated transverse Λ polarizations:
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The CKM parameters:
The weak phase γ:
At the scale mb and Nc=3:
PDG, Phys. Lett. B592 (2004) 1.
γ=600 (,)=(0.20,0.35)
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To observe T violating asymmetries of 10—7% at 2 level
Need ~
♥ The SM effect
For the rate CP asymmetry:
Too small to be observed!
☺ It is accessible at the current B-factories and could be the first process to observe direct T violating effect!!!
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Using the generalized factorization method:
Amplitude:
C. Q. Geng and Y. K. Hsiao, arXiv:hep-ph/0503264.
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T-odd TPC asymmetries in the standard model
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● Some Remarks:
a. Nonfactorizable effects are small for and
b. The errors due to the CKM and other fitting parameters are expected to be less than 10%
d. An interesting mode:
● The indirect (mixing-induced) CP asymmetry: sin 2β
● The direct (rate) CP asymmetry: ACP = O(1%)
● The direct T asymmetry: AT = O(1%)
Too small
c. The final state interactions have been ignored (see H.Y.Cheng’s talk)
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4. Summary♠ The triple momentum correlations in baryonic B decays are unique observables to search for T violation.
♥ There are many possible three-body baryonic B decays in which T violating effects can be large.
♦ They are accessible at the current B-factories.
♣ They could be the first measurable direct T violating effects.
In the standard model
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Thank you!
謝謝!
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● Calculation the decay branching ratio
Matrix elements and form factors:
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Input parameters:
QCD counting rules:
The effective Wilson coefficients (WCs):
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