C.Q. Geng ( 耿朝強）

National Tsing Hua University

(The 3rd Int. Conf. on Flavor Physics, NCU, Oct. 3-8, 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

● Work done with Dr. Y.K. Hsiao.

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

→

☺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’)

See HY.Cheng’s Talk

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

3. T violating effects in baryonic B decays

Using the generalized factorization method:

C. Q. G.+Y.K. HsiaoPRD72:037901,2005

Chua, Hou,Tsai, PRD66 (2002) 054004.

Chua,Hou, Eur. Phys. J. C 29 (2003) 27..

(see Hsiao’s talk)

Four components of Λ spin:

Three polarization directions:

The longitudinal, normal and transverse Λ polarizations:

The Integrated transverse Λ polarizations:

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)

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!!!

Using the generalized factorization method:

Amplitude:

C. Q. G + Y. K. Hsiao, PLB619:305,2005.

T-odd TPC asymmetries in the standard model

● 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 C.K.Chua’s talk)

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

Thank you!

謝謝！

● Calculation the decay branching ratio

Matrix elements and form factors:

Input parameters:

QCD counting rules:

The effective Wilson coefficients (WCs):