EPS03, July 17-23, 2003

Lorenzo Vitale 1

Time dependent CP violation studies in D(*)D(*) and J/ψ K*

Lorenzo VitaleINFN Trieste

On behalf of

BaBar and BelleCollaborations

EPS03, July 17-23, 2003

Lorenzo Vitale 2

Outline

In this talk I take for granted CP(t) fit technique @ B-factories and measurements with charmonium KS,L sin(2) = 0.731 ± 0.055

1. How and why study D(*)D(*) and J/ψ K*?

2. D*+D*-: BF, CP-odd fraction# and CP(t) analysis#

3. D*+D-, D+D*-: BF# and CP(t) analysis#

4. J/ψ K*: amplitudes

5. Summary # new or updated

results

EPS03, July 17-23, 2003

Lorenzo Vitale 3

Vector-Vector decays

B0 D*+D*- and J/ψ K*0(Ksπo) not pure CP eigenstates

Vector-Vector decays with three partial waves S, P, D

Transversity amplitudes: A0, A|| (CP = +1 even), A (CP = -1 odd)

CP(t) studies are more complicated:

Simplest method:

define CP-odd fraction R = |A|2 /(|A0|2 + |A|| |2 + |A|2)

CP asymmetry diluted by K = (1 - 2R)

Otherwise use angles:

2D: Only one angle (transversity)

4D: All angles (full angular)

EPS03, July 17-23, 2003

Lorenzo Vitale 4

Why to study V-V and bcdc decays?

b

d d

Wccd )(D

)(D0B0B

t,c,ub

dd

W

d

)(D

c

cg

)(D

B0 D(*)D(*) : bcdc Cabibbo suppressed tree + penguin

Tree measures sin2 from bcdc transitions (consistency with J/ψKS,L )Penguin are expected to be small in SM (<10%)but can be enhanced by new physics

D*+D-, D+D*-: non-CP eigenstate

J/ψ K*0(Ksπo): from interference between CP-even and CP-odd

amplitudes cos2 term (not in this talk)

EPS03, July 17-23, 2003

Lorenzo Vitale 5

B0 D*+D*-

Experimentally:

events reconstructed from exclusive D*(D) decays; in total ~20 modes used.

BaBar

Belle

Systematic uncertainty dominated by tracking efficiency and partial waves composition (two soft pions)

BaBar PRL 89, 061801 (2002) with 20fb-1

BF(B0 D*+D*-) = ( 8.3 1.6 1.2 )x10-4

Belle preliminary ICHEP02 with 78fb-1

BF(B0 D*+D*-) = ( 7.6 0.9 1.4 )x10-4

EPS03, July 17-23, 2003

Lorenzo Vitale 6

D*+D*- CP-odd fraction R :Time integrated transversity

analysisθtr

Transversity frame

2 21 d 3 3(1 )sin cos

d cos 4 2tr trtr

R R

Systematic uncertainty dominated by acceptance and θtr

resolution

BaBar (hep-ex/0306052) new with 81fb-1

R = 0.063 0.055 0.009

BaBar 15614 signal events

EPS03, July 17-23, 2003

Lorenzo Vitale 7

D*+D*- CP(t) angular analysis (BaBar)

K = 1 – 2R┴ angular dilution

2D analysis: combined time, tag, cosθtr

If penguin diagrams non-negligible different 0, ||, ┴

Define CP-even parameter + as weighted average of 0, ||

No sensitivity on CP-odd ┴ (fixed in the fit)Decay rate

f±(θtr,t) exp(–|t|/B) { G(i,K;θtr) ±

[S(i,K;θtr) sin(mt) – C(i,K;θtr) cos(mt)] }

EPS03, July 17-23, 2003

Lorenzo Vitale 8

D*+D*- CP(t) angular analysis (BaBar)

BaBar (hep-ex/0306052)

New with 81fb-1

Im = 0.05 0.29 0.10

= 0.75 0.19 0.02

Two largest systematic uncertainties: wide variation of the CP of bkg

and λ┴

t (ps)

EPS03, July 17-23, 2003

Lorenzo Vitale 9

Interpretation of the results

•Complex parameter :

if penguin contribution negligible Im = -sin2 , = 1

Some models, based on factorization and HQET predict penguin dilution of sin(2) of ~2%, e.g. X.Y.Pham and Z.Z.Xing, Phys.Lett.B 458, 375 (1999)

•CP-odd fraction:agrees with some predictions based on factorization and HQET e.g. 6% by J.L. Rosner Phys. Rev. D 42, 3732 (1990)

Redoing the fit assuming measurements from charmonium system

(fixing -Im to sin2 from charmonium modes and =1)

… change in Likelihood corresponds to 2.5σ effect (stat only).

Interesting, but it could still be just a statistical fluctuation.

EPS03, July 17-23, 2003

Lorenzo Vitale 10

B0 D*±D

±

exclusive reconstruction in ~10 sub-modes

BaBar113±13 ev.Belle 30±7 ev.

Systematic uncertainty dominated by tracking efficiency, Br(D) and peaking background

Belle PRL 89, 122001 (2002) with 29fb-1 BF(B0 D*D) = (11.7 2.6 2.3)x10-4

BaBar PRL 90, 221801 (2003) with 81fb-1

BF(B0 D*D) = (8.8 1.0 1.3 )x10-4

Two largest systematic uncertainties: soft pion charge asymmetry and mES resolution

Time-integrated rate asymmetry (BaBar)

EPS03, July 17-23, 2003

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D*D time dependent analysis (BaBar)

Not a CP eigenstate: use the S & C parametrization for decay rate f ±

If equal amplitudes for B0D*-D+ and B0 D*+D- and penguins negligible: C=0, S=-sin(2)

Two largest systematic uncertainties: peaking bkg fraction and CP of peaking bkg

f±(t) exp(–|t|/B) { 1 ± [S sin(mt) – C cos(mt)]

}BaBar PRL 90, 221801 (2003) with 81fb-1

EPS03, July 17-23, 2003

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J/ψ K* angular analysis

Only J/K* (K* KS0) is a (mixture of) CP eigenstates

But for time integrated full angular analysis

also B0 J/K*0(K+-) and B+ J/K*+(K+0,KS+) can be used.

CP-odd fraction small (but not negligible)

arg(A||) inconsistent with π expectation from

factorization

BaBar, PRL87 (2001) 241801

Belle, PLB538 (2002) 11-20

|A0|2 0.60 ± 0.03 ± 0.02 0.62 ± 0.02 ± 0.03

|A|2 0.16 ± 0.03 ± 0. 01 0.19 ± 0.02 ± 0. 03

arg(A||)2.50 ± 0.20 ± 0.08 2.83 ± 0.19 ± 0.08

arg(A) -0. 17 ± 0.16 ± 0. 07 -0. 09 ± 0.13 ± 0. 06

EPS03, July 17-23, 2003

Lorenzo Vitale 13

Summary•CP(t)+angular analysis for V-V modes can be handled

•CP-odd fractions are small both in B0 D*+D*- and B0J/ K*0(K+p-)

•In bcdc modes like D(*)D(*) penguin-induced corrections expected to be small, but can be enhanced by new physics

•A comparison with charmonium is an important test of SM

•Results are interesting, but …need more data!

EPS03, July 17-23, 2003

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Backup slides

EPS03, July 17-23, 2003

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CP(t) asymmetries: fit technique

CPV in mixing-decay interference direct CPV

f±(t) exp(–|t|/B) ( 1 ± D (S sin(mt) - C cos(mt)) ) R

2

2

21

1

1

2

CSB0

B0

fCP

CP eigenvalue

Mi

tdtb

tdtb eVV

VV

p

q 2

*

*

Amplitude ratio B0fcp/B0fcp

B mixing

D mis-tag dilutionR time resolution

Measured from data

EPS03, July 17-23, 2003

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Transversity frame

The momenta of D*- decay products are represented in the B rest frame, while the momenta of D*+ decay products are represented in the D*+ rest frame.

EPS03, July 17-23, 2003

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D*+D*- Time dependent angular analysis

2 2|| 0

2 2|| 0

|| 02 2

|| 0

(1 | | ) (1 | | )0 2 0 2|| 0(1 | | ) (1 | | )

0 2 0 2|| 0

2 ( ) 2 ( )0 2 0 2|| 0(1 | | ) (1 | | )

0 2

2

2

0| 0

2 2|

| | | |

| | | |

| | | |

| | | |

(1 | | )

(1 | | )

2

(1 | | )

( )

A A

A A

A A

A A

2

22

2

22

(1 |(1 | | )

(1 |

2

| )

2 ( )

(

23 1 14 2 2

2 23 1 14 2 2

2 2

| )

(1 | | )

2 ( )

(13

| | ) 11 1

4 2 2 | | )

(1 )sin (1 ) 2cos

(1 )sin (1 ) 2cos

(1 )sin (1 ) 2cos

tr tr

tr tr

tr tr

O K K

C K K

S K K

CP even parameters CP odd parametersCP angulardilution factor: K = 1 – 2R┴

EPS03, July 17-23, 2003

Lorenzo Vitale 18

Sensitivity in angular CP(t) analysis

O 1D: Treat R as dilution

2D: Use tr

4D: Full angular analysis