Penguin Dominated CP Violation, DCPV and Search for New Physics

Yee B. Hsiung, National Taiwan University

5th Rencontres du Vietnam

Hanoi, 6-11th August 2004

Introduction to

PenguinRadiative Penguin

DecaysDCPVStatus & Perspective

CP Violation by Kobayashi-Maskawa

2

2

)1(

2/

)(2/

AiA

A

iA

VVV

VVV

VVV

tbtstd

cbcscd

ubusud

KM ansatz: CP violation is due tocomplex phase in quark mixing matrixKM ansatz: CP violation is due tocomplex phase in quark mixing matrix

unitarity triangle

CP violation parameters(1, 2, 3) = (, , )

CP violation parameters(1, 2, 3) = (, , )

Time Dependent CP Asymmetry

0 0

0 0

0 0

( ) ( )( ) sin cos

( ) ( )

d CP d CPB B

d CP d CP

B f B fA t m At m

B f fS t

B

2

2 2

: eigenvalue

2 Im( ) | | 1,

| | 1 | | 1

f

AS

CP

S = f sin21: SM prediction

A = 0 or || = 1 No direct CPV

Inputs: f = 1, S = 0.6A = 0.0

0d CPB f0

d CPB f

f

q

p

Af

Af

CP

CP

CP

New Physics Hunting in b sqq

New Physics Hunting in b sqq

SM predicts same CPV in b ccs and sqq.

SM predicts same CPV in b ccs and sqq.

SM penguinSM penguin

+

New process w/ different CP phase

New process w/ different CP phase

e.g.) squark penguin

New physics may deviate CPV in b ccs from sqq New physics may deviate CPV in b ccs from sqq

Deviation from b ccs Hint of new physics !

Tree vs Penguin

The KEK-B Collider

3.5 GeV e+ on 8 GeV e-

L > (1.3 x 1034)/cm2/sec

L dt = 286.8 fb-1

274 M BB pairs!

Y(4S)

The Belle Detector @KEK

3 layersSilicon Vertex Detector

4 layers

Central Drift Chamber

8 GeV e-

3.5 GeV e+

Aerogel Cherenkov Counter

ToF counter

Electromagnetic. Cal.(CsI crystals)

1.5T SC solenoid

and KL detection system

The BaBar Detector @SLAC

CP Violation in b ccs

5417 events @ 152M BB

1sin 2

0.733 0.057 0.028

1sin 2

0.733 0.057 0.028

1.007 0.041 (stat)ccs consistent with no Direct CPV

poor flavor tag

fine flavor tag

Small systematic uncertainty

Well controlled analysis technique

Small systematic uncertainty

Well controlled analysis technique

b sqq Reconstructionsb sqq Reconstructions

•B0 KS : K+K, KS +

•Minimal kaon-identification requirements.•Belle standard KS selection.•| M(KK) M() | < 10MeV/c2 (mass resolution = 3.6 MeV/c2).•| p| in CMS > 2.0 GeV/c.•Belle standard continuum suppression. •| E | < 60MeV, 5.27 < Mbc < 5.29 GeV/c2.

M(KK) [GeV/c2]

• Background is dominated by continuum• CP in the background:

– KKKS: (7.2±1.7)%– f 0(980)KS:– These effects are included in the systematic error.

• Background is dominated by continuum• CP in the background:

– KKKS: (7.2±1.7)%– f 0(980)KS:– These effects are included in the systematic error.

B 0 KS

B 0 KKKS

B 0 KS

2 cms 2 cms 2bc beam(GeV/ ) ( ) ( )BM c E p

6811 signals106 candidates for S and A fitpurity = 0.640.10efficiency = 27.3%

24421 signals421 candidates for S and A fitpurity = 0.580.05efficiency = 17.7% (´ ) 15.7% (´ )

19918 signals361 candidates for S and A fitpurity = 0.550.05efficiency = 15.7%

CP Violation in b sqqCP Violation in b sqq

@ 152M BB

CP Violation in b sqqCP Violation in b sqq

B0 KS B0 KKKS B0 ’KS

B fCP(sqq) decay vertices are reconstructed using K- or - track pair.

Fit sin21

@ 152M BB

-fS

A

09.011.050.096.0

07.029.015.0

18.000.005.026.051.0

04.016.017.0

05.027.043.0

04.016.001.0

Statistical SignificanceStatistical Significance

Hint of new physics?Need more data to establish conclusion.

Hint of new physics?Need more data to establish conclusion.

B0 KKKS, ´KS

Consistent with sin21.

B0 KS

3.5 deviation (Feldman-Cousins).S(KS) = sin21: 0.05% probability.

K. Abe et al. [Belle collaboration], PRL 91, 261602 (2003)

Smoking gun?

Summary of sin2()

3.5

2.4

Another smoking gun?

Comparing with B

~100% longitudinally polarized

Radiative Penguin Decays

b -> s and b -> sl+l- decays proceed via

flavour changing neutral current (FCNC)

box and penguin diagrams

b -> s penguin:

BR(b->s3.5 10-4

Not so rare actually…

b -> sl+l- penguin: b -> sl+l- box:

+

BR(b->sl+l-emBR(b->s) 10-6 !!!

New particles can/will contribute quite significantly to the decay rates and various asymmetries quite significantly

via the loops!=> Ideal testing ground for SM and extensions

(2HDM, MSSM, GUT, …?)

Radiative Penguin Results

BR(B -> XSll )

BR(B -> XSll )

BR(B -> XSll)

Check MXs and Mll mass

ACP(B -> K*)

Update ACP(B -> K*)

b->sPhoton Energy Spectrum

Search for b->d

BaBar Results on b->d Search

Belle Results on b->dSearch

More in Parrallel session

There are lots of them…

Direct CP Violation in

Direct CP Violation in

3.2DCPV

PRL 93, 021601 (2004)

ACP in Charmless B Decays

Acp(K+-)

World average

Hint of DCPV?

More ACP in Charmless B Decays

BaBar’s new ACP for K+-

Acp(K+-) =-0.1330.0300.009B. Aubert et al.,hep-ex/0407057

Acp(K+-) =-0.0880.0350.013Belle

newBaBar

Y. Chao et al.,hep-ex/0407025

Status and Prospect

• Smoking gun results in Penguin dominated processes, such as KS and K* have been around the corner.

More data is needed to clarify the situation. But soon we shall find out the answer.

• Radiative Penguin decays are ideal testing ground for SM

and new physics. However, no smoking gun yet!

Need more data to fix some of the important parameters

in

EW/radiative penguin transitions

• Direct CP Violation in B-decays may surface very soon.

Many interesting discoveries are still ahead…

Future Prospect of Measurements

Future Prospect of Measurements

ab-1

ab-1

ab-1

Going forSuper B factory