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

1. Time dependent CP violation studies in D(*)D(*) and J/ψ K* Lorenzo Vitale INFN Trieste On behalf of BaBar and Belle Collaborations Lorenzo Vitale

2. Outline • How and why study D(*)D(*) and J/ψ K*? • D*+D*-: BF, CP-odd fraction# and CP(t) analysis# • D*+D-, D+D*-: BF# and CP(t) analysis# • J/ψ K*: amplitudes • Summary • # new or updated results In this talk I take for granted CP(t) fit technique @ B-factories andmeasurements with charmonium KS,L sin(2b) = 0.731 ± 0.055 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 = +1even), 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) Lorenzo Vitale

4. 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/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 cos2b term (not in this talk) Lorenzo Vitale

5. B0 D*+D*- Experimentally: events reconstructed from exclusive D*(D) decays; in total ~20 modes used. BaBar 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 Belle Systematic uncertainty dominated by tracking efficiency and partial waves composition (two soft pions) Lorenzo Vitale

6. D*+D*- CP-odd fraction R:Time integrated transversity analysis θtr BaBar 15614 signal events Transversity frame BaBar (hep-ex/0306052) new with 81fb-1 R= 0.063  0.055  0.009 Systematic uncertainty dominated by acceptance and θtr resolution Lorenzo Vitale

7. D*+D*- CP(t) angular analysis (BaBar) 2D analysis: combined time, tag, cosθtr If penguin diagrams non-negligible  differentl0, l||, l┴ Define CP-even parameterl+ as weighted average of l0, l|| No sensitivity on CP-oddl┴ (fixed in the fit) Decay rate f±(θtr,Dt)  exp(–|Dt|/tB) {G(li,K;θtr) ± [S(li,K;θtr) sin(DmDt) – C(li,K;θtr) cos(DmDt)]} K = 1 – 2R┴angular dilution 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┴ Dt (ps) Lorenzo Vitale

9. Interpretation of the results • CP-odd fraction: • agrees with some predictions based on factorization and HQET • e.g. 6% byJ.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 2.5σeffect (stat only). Interesting, but it could still be just a statistical fluctuation. Lorenzo Vitale

10. B0 D*±D BaBar113±13 ev. Belle 30±7 ev. Time-integrated rate asymmetry (BaBar) Two largest systematic uncertainties: soft pion charge asymmetry and mES resolution ± exclusive reconstruction in ~10 sub-modes 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 Systematic uncertainty dominated by tracking efficiency, Br(D) and peaking background Lorenzo Vitale

11. D*Dtime dependent analysis (BaBar) BaBar PRL 90, 221801 (2003) with 81fb-1 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 D*+D- and penguins negligible: C=0, S=-sin(2b) Lorenzo Vitale

12. J/ψ K* angular analysis Only J/yK* (K* KSp0) is a (mixture of) CP eigenstates But for time integrated full angular analysis also B0J/yK*0(K+p-) and B+ J/yK*+(K+p0,KSp+) can be used. CP-odd fraction small (but not negligible) arg(A||) inconsistent with π expectation from factorization Lorenzo Vitale

13. Summary • In bcdc 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! • CP(t)+angular analysis for V-V modes can be handled • CP-odd fractions are small both in B0 D*+D*- and B0J/y K*0(K+p-) Lorenzo Vitale

14. Backup slides Lorenzo Vitale

15. CP(t) asymmetries: fit technique B0 fCP B0 Amplitude ratio B0fcp/B0fcp CP eigenvalue B mixing 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 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. Lorenzo Vitale

17. D*+D*- Time dependent angular analysis CP odd parameters CP even parameters CP angular dilution factor: K = 1 – 2R┴ Lorenzo Vitale

18. Sensitivity in angular CP(t) analysis O 1D: Treat R as dilution  2D: Use qtr 4D: Full angular analysis Lorenzo Vitale