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B → Kπ decays and new physics in the EW-penguin sector

Yu, Chaehyun (Yonsei University)

October 6, 2005

In Collaboration with C.S. Kim, S. Oh J.H. Jeon, C.S. Kim, Jake Lee

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Outline

puzzle puzzle

Numerical analysisNumerical analysis

Flavor changing model andFlavor changing model and

ConclusionConclusion

B K p®

Z¢ B K nn®

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B → KB → Kππ decays decays

4 decay channels ( and anti-particle decay 4 decay channels ( and anti-particle decay channels)channels)

All branching ratios are well measured All branching ratios are well measured within 10% errors.within 10% errors.

Direct CP asymmetry in B → KDirect CP asymmetry in B → K++ππ-- has been has been observed at the 5.7observed at the 5.7σσ level. level.

Other CP asymmetries have rather large Other CP asymmetries have rather large errors.errors.

Conventional SM prediction is not Conventional SM prediction is not consistent with the current data.consistent with the current data.

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All observables are All observables are measured. measured.

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SM : SM : 0c nR R- :

Puzzle in Branching Puzzle in Branching Ratios Ratios

a considtent pattern by CLEO, BABAR, a considtent pattern by CLEO, BABAR, BELLEBELLE

1nR <

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Puzzle in Direct CP Puzzle in Direct CP Asymmetry Asymmetry

0( ) 0.115 0.018CPA B K p+- ±® = - ±m

0 0( ) 0.04 0.04CPA B K p+ ± ±® = ±0 : 3.5CP CPA A s+- +-

SM : SM : 0CP CPA A+- +- :

Large strong phases are required. Large strong phases are required.

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Puzzle in Indirect CP Puzzle in Indirect CP Asymmetry Asymmetry

0.34 0.29sK

Sp0 = + ±

sin(2 0.725 0.037f 1) = + ±IInn

(*)/ ,B J Ky®

1sin(2 ) : 1.32sK

Sp

f s0 -

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All data

4 BRs only

Large rc

Large rEW

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Best fit values are

Large rc

Large rEW

Charnng, Li;Charnng, Li;

He, McKellar;He, McKellar;

Wu, Zhou;Wu, Zhou;

Mishima, Mishima, Yoshikawa;Yoshikawa;

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Why rWhy rCC is so large? is so large?

In the conventional hierarchy (rIn the conventional hierarchy (rCC = 0.02), = 0.02),

But, experimental data show 1.32But, experimental data show 1.32σσ deviation. deviation.

0.34 0.29sK

Sp0 = + ±

This may indicate that the subleading terms including rThis may indicate that the subleading terms including rCC and rand rEWEW play an important role. play an important role.

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The parameter rc is sensitive to the observable

SKs

Sensitivity Sensitivity checkcheck

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New Physics in EW penguin New Physics in EW penguin sector ?sector ?Large Enhancement in rLarge Enhancement in rCC is very difficult in the SM and in New is very difficult in the SM and in New

Physics because it is related to the color-allowed tree Physics because it is related to the color-allowed tree amplitude.amplitude.

Small rSmall rCC solution can be relieved by new physics with weak solution can be relieved by new physics with weak phase in EW penguin sector.phase in EW penguin sector.

cf. Baek, Hamel, London, Datta, Suprun, PRD71, cf. Baek, Hamel, London, Datta, Suprun, PRD71, 057502 (2005) 057502 (2005)

EWSM NP( is assumed.)d d=

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Leptophobic ZLeptophobic Z΄́ ModelModel

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Z-mediated vs. ZZ-mediated vs. Z΄́-mediated FCNC-mediated FCNC

Possible scenarios in GUT model (EPossible scenarios in GUT model (E66 model). model).

Z-mediated FCNC are constrained byZ-mediated FCNC are constrained by

0 0

, | ,

( ), - mixing, CP asymmetries...

K LM K

B B l l X B B

e m m+ -

+ -

D |, ®

®

Originally leptophobic ZOriginally leptophobic Z΄́ model was introduced to explain model was introduced to explain RRbb-R-Rcc puzzle at LEP puzzle at LEP

→ → Now, original motivation disappears.Now, original motivation disappears.

Constraints on leptophobic ZConstraints on leptophobic Z΄́ model may be weaker than model may be weaker than other Zother Z΄́- or Z-mediated FCNC models.- or Z-mediated FCNC models.

However, it still remains as a viable candidate of new physics.However, it still remains as a viable candidate of new physics.

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Brief review of leptophobic ZBrief review of leptophobic Z΄́ modelmodel

SU(2)SU(2)LLxU(1)xU(1)YYxU(1)xU(1)΄́ : U(1) : U(1)΄́ arise from the breaking chain arise from the breaking chain

with with QQ΄́=Q=Qψψ cos cos θθ – Q – Qχχ cos cos θθ, , wherewhere θθ is the usualis the usual E E66 mixing mixing angleangle

Leroux, London, Leroux, London, PLB526,97(2002)PLB526,97(2002)

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The most general SU(2)The most general SU(2)LLxU(1)xU(1)YYxU(1)xU(1)΄́ invariant Lagrangian invariant Lagrangian include a kinetic mixing term between U(1)include a kinetic mixing term between U(1)Y Y and U(1)and U(1)΄́ gauge bosons:gauge bosons:

With the non-unitarity transformationWith the non-unitarity transformation

ZZ΄́-fermion interaction term can be written-fermion interaction term can be written

Leptophobic ZLeptophobic Z΄́ if tan if tan θθ = √ 3/5 and = √ 3/5 and δδ = -1/3 for conventional = -1/3 for conventional embedding.embedding.

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Parametrize ZParametrize Z΄́- mediated FCNC coupling as- mediated FCNC coupling as

ZZ΄́ does not couple to SM neutrino because it is does not couple to SM neutrino because it is leptophobic.leptophobic.

However, it does couple to the right-handed neutrino (However, it does couple to the right-handed neutrino (ννcc or Sor Scc).).

Tree level FCNC in B decaysTree level FCNC in B decays

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, , , ...B X Knn nn pnn®

Leptophobic ZLeptophobic Z΄́ model and B model and B decaysdecays

New physics in EW penguin sector? – where can we New physics in EW penguin sector? – where can we confirm it?confirm it?

EW penguin dominant processes is most prominent for EW penguin dominant processes is most prominent for such NP. such NP. , b s B Xllg® , ® L

If new physics is leptophobic, we can resort to If new physics is leptophobic, we can resort to

ZZ΄́ mass bound (CDF) mass bound (CDF)

600 GeVZM ¢ >

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max 0.29ZsbU ¢ =

Cf. from inclusive decay bCf. from inclusive decay b→s→sνννν at at ALEPHALEPH

0.83ZsbU ¢ <

700 GeVZM ¢ =

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max 0.61ZdbU ¢ =

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ConclusionConclusion

Current data implies large enhancements Current data implies large enhancements in rin rCC and r and rEWEW..

New physics in EW penguin sector may New physics in EW penguin sector may solve solve B B →→ K Kππ puzzle. puzzle.

But, the evidence for new physics is not But, the evidence for new physics is not decisive.decisive.

EW penguin dominant processes can serve EW penguin dominant processes can serve as a probe of new physics in the EW as a probe of new physics in the EW penguin sector.penguin sector.

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Theoretical Expectation Theoretical Expectation

CharminCharming g PenguinPenguinss

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SM : SM : 0 up to ( )c nR R O r- :

Enhancements in sub-dominant components Enhancements in sub-dominant components can lead to a sizable deviation in Rcan lead to a sizable deviation in Rcc-R-Rnn . .

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SM : SM : 0 0 up to ( )CP CPA A O r+ +-- :

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NLO in PQCD NLO in PQCD

Recently the NLO calculation including vertex correction, Recently the NLO calculation including vertex correction, quark loop, and magnetic penguin in PQCD has been done quark loop, and magnetic penguin in PQCD has been done (Li, Mishima, Sanda, hep-ph/0508041)(Li, Mishima, Sanda, hep-ph/0508041)

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Although BRs and direct CP asymmetries are explained well Although BRs and direct CP asymmetries are explained well in NLO in PQCD, the indirect CP asymmetries are inconsistent in NLO in PQCD, the indirect CP asymmetries are inconsistent with current data, but almost same to the conventional SM with current data, but almost same to the conventional SM prediction.prediction.