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3 EPS03, July 17-23, 2003Lorenzo Vitale Vector-Vector decays B 0 D* + D* - and J/ψ K* 0 (K s π o ) not pure CP eigenstates Vector-Vector decays with three partial waves S, P, D Transversity amplitudes: A 0, A || ( CP = +1 even), A ( CP = -1 odd) CP(t) studies are more complicated: Simplest method: define CP-odd fraction R = |A | 2 /(|A 0 | 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)
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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 ofBaBar and Belle
Collaborations
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 decaysB0 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?
bd d
Wccd )(D
)(D0B0B
t,c,ub
dd
W
d
)(D
cc
g)(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 eigenstateJ/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
BelleSystematic 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 cosd cos 4 2tr tr
tr
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 ratef±(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-modesBaBar113±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
Lorenzo Vitale 11
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
Lorenzo Vitale 12
J/ψ K* angular analysisOnly J/K* (K* KS0) is a (mixture of) CP eigenstatesBut 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
Lorenzo Vitale 14
Backup slides
EPS03, July 17-23, 2003
Lorenzo Vitale 15
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
2 1
1
12
CSB0
B0
fCP
CP eigenvalueMi
tdtb
tdtb eVVVV
pq 2
*
*
Amplitude ratio B0fcp/B0fcp
B mixing
D mis-tag dilutionR time resolution
Measured from data
EPS03, July 17-23, 2003
Lorenzo Vitale 16
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
Lorenzo Vitale 17
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 ( )(1
3| | ) 1
1 14 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
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