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

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

• Lorenzo Vitale
• INFN Trieste

On behalf of BaBar and
Belle Collaborations
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Outline

• How and why study D()D() and J/? K?
• DD- BF, CP-odd fraction and CP(t) analysis
• DD-, DD- BF and CP(t) analysis
• J/? K amplitudes
• Summary
• new or updated results

In this talk I take for granted CP(t) fit
technique _at_ B-factories and measurements with
charmonium KS,L sin(2b) 0.731 0.055
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Vector-Vector decays
B0? DD- and J/? K0(Kspo) 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 /(A02 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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Why to study V-V and b?cdc decays?
B0? D()D() b?cdc Cabibbo suppressed tree
penguin
Tree measures sin2b from b?cdc transitions
(consistency with J/?KS,L ) Penguin are expected
to be small in SM (lt10) but can be enhanced by
new physics DD-, DD- non-CP eigenstate J/?
K0(Kspo) from interference between CP-even and
CP-odd
amplitudes cos2b term (not in this talk)
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B0? DD-
Experimentally events reconstructed from
exclusive D(D) decays in total 20 modes used.
BaBar
BaBar PRL 89, 061801 (2002) with 20fb-1 BF(B0?
DD-) ( 8.3 ? 1.6 ? 1.2 )x10-4 Belle
preliminary ICHEP02 with 78fb-1 BF(B0? DD-)
( 7.6 ? 0.9 ? 1.4 )x10-4
Belle
Systematic uncertainty dominated by tracking
efficiency and partial waves composition (two
soft pions)
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DD- CP-odd fraction R ? Time integrated
transversity analysis
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DD- CP(t) angular analysis (BaBar)
2D analysis combined time, tag, cos?tr If
penguin diagrams non-negligible ? different l0,
l, l- Define CP-even parameter l as weighted
average of l0, l No sensitivity on CP-odd l-
(fixed in the fit)
Decay rate f(?tr,Dt) ? exp(Dt/tB)
G(li,K?tr) S(li,K?tr)
sin(DmDt) C(li,K?tr) cos(DmDt)
K 1 2R- angular dilution
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DD- 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 ?-
Dt (ps)
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Interpretation of the results

• 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)

• Complex parameter ??
• if penguin contribution negligible Im?? -sin2b
  , ???? 1
• Some models, based on factorization and HQET
  predict penguin dilution of sin(2b) of 2, e.g.
  X.Y.Pham and Z.Z.Xing, Phys.Lett.B 458, 375 (1999)

Redoing the fit assuming measurements from
charmonium system (fixing -Im?? to sin2b from
charmonium modes and ????1) change in
Likelihood corresponds to 2.5s effect (stat
only). Interesting, but it could still be just a
statistical fluctuation.
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B0? DD

exclusive reconstruction in 10 sub-modes
Belle PRL 89, 122001 (2002) with 29fb-1 BF(B0?
DD) (11.7? 2.6 ? 2.3)x10-4 BaBar PRL 90,
221801 (2003) with 81fb-1 BF(B0? DD) (8.8 ?
1.0 ? 1.3 )x10-4
Systematic uncertainty dominated by tracking
efficiency, Br(D) and peaking background
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DD time dependent analysis (BaBar)
Not a CP eigenstate use the S C
parametrization for decay rate f
f(Dt) ? exp(Dt/tB) 1 S sin(DmDt) C
cos(DmDt)
Two largest systematic uncertainties peaking bkg
fraction and CP of peaking bkg
If equal amplitudes for B0?D-D and B0? DD-
and penguins negligible C0, S-sin(2b)
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J/? K angular analysis
Only J/yK (K? KSp0) is a (mixture of) CP
eigenstates But for time integrated full angular
analysis also B0? J/yK0(Kp-) and B?
J/yK(Kp0,KSp) can be used.
BaBar, PRL87 (2001) 241801 Belle, PLB538 (2002) 11-20
A02 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
CP-odd fraction small (but not negligible) arg(A
) inconsistent with p expectation from
factorization
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Summary

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

• CP-odd fractions are small both in B0? DD- and
  B0?J/y K0(Kp-)

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Backup slides
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CP(t) asymmetries fit technique
CPV in mixing-decay interference
direct CPV f(Dt) ?? exp(Dt/tB) ( 1 D (S
sin(DmDt) - C cos(DmDt)) ) ? R
D mis-tag dilution R time resolution
Measured from data
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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.
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DD- Time dependent angular analysis
CP odd parameters
CP even parameters
CP angular dilution factor K 1 2R-
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Sensitivity in angular CP(t) analysis