1 EPS03, July 17-23, 2003Lorenzo Vitale Time dependent CP violation studies in D(*)D(*) and J/ψ K* Lorenzo Vitale INFN Trieste On behalf of BaBar and Belle Collaborations

2 EPS03, July 17-23, 2003Lorenzo Vitale Outline In this talk I take for granted CP(t) fit B-factories and measurements with charmonium K S,L sin(2  ) = ± 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

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)

4 EPS03, July 17-23, 2003Lorenzo Vitale Why to study V-V and b  cdc decays? B 0  D ( * ) D ( * ) : b  cdc Cabibbo suppressed tree + penguin Tree measures sin2  from b  cdc transitions (consistency with J/ψK S,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 (K s π o ): from interference between CP-even and CP-odd amplitudes cos2  term (not in this talk)

5 EPS03, July 17-23, 2003Lorenzo Vitale B 0  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, (2002) with 20fb -1 BF(B 0  D* + D* - ) = ( 8.3  1.6  1.2 )x10 -4 Belle preliminary ICHEP02 with 78fb -1 BF(B 0  D* + D* - ) = ( 7.6  0.9  1.4 )x10 -4

6 EPS03, July 17-23, 2003Lorenzo Vitale D* + D* - CP-odd fraction R  : Time integrated transversity analysis θ tr Transversity frame Systematic uncertainty dominated by acceptance and θ tr resolution BaBar (hep-ex/ ) new with 81fb -1 R  =   BaBar 156  14 signal events

7 EPS03, July 17-23, 2003Lorenzo Vitale D* + D* - CP(t) angular analysis (BaBar) K = 1 – 2R ┴ angular dilution 2D analysis: combined time, tag, cos θ tr 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 ± (θ tr,  t)  exp(–|  t|/  B ) { G( i,K;θ tr ) ± [ S( i,K;θ tr ) sin(  m  t) – C( i,K;θ tr ) cos(  m  t) ] }

8 EPS03, July 17-23, 2003Lorenzo Vitale D* + D* - CP(t) angular analysis (BaBar) BaBar (hep-ex/ ) 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)

9 EPS03, July 17-23, 2003Lorenzo Vitale 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.

10 EPS03, July 17-23, 2003Lorenzo Vitale B 0  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, (2002) with 29fb -1 BF(B 0  D*D) = (11.7  2.6  2.3)x10 -4 BaBar PRL 90, (2003) with 81fb -1 BF(B 0  D*D) = (8.8  1.0  1.3 )x10 -4 Two largest systematic uncertainties: soft pion charge asymmetry and m ES resolution Time-integrated rate asymmetry (BaBar)

11 EPS03, July 17-23, 2003Lorenzo Vitale D*D time dependent analysis (BaBar) Not a CP eigenstate: use the S & C parametrization for decay rate f ± If equal amplitudes for B 0  D* - D + and B 0  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(  m  t) – C cos(  m  t) ] } BaBar PRL 90, (2003) with 81fb -1

12 EPS03, July 17-23, 2003Lorenzo Vitale J/ψ K* angular analysis Only J/  K* (K*  K S  0 ) is a (mixture of) CP eigenstates But for time integrated full angular analysis also B 0  J/  K* 0 (K +  - ) and B +  J/  K* + (K +  0,K S  + ) can be used. CP-odd fraction small (but not negligible) arg(A || ) inconsistent with π expectation from factorization BaBar, PRL87 (2001) Belle, PLB538 (2002) |A 0 | ± 0.03 ± ± 0.02 ± 0.03 |A|2|A| ± 0.03 ± ± 0.02 ± arg(A || ) 2.50 ± 0.20 ± ± 0.19 ± 0.08 arg(A  ) ± 0.16 ± ± 0.13 ± 0. 06

13 EPS03, July 17-23, 2003Lorenzo Vitale Summary CP(t)+angular analysis for V-V modes can be handled CP-odd fractions are small both in B 0  D* + D* - and B 0  J/  K* 0 (K + p - ) 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!

14 EPS03, July 17-23, 2003Lorenzo Vitale Backup slides

15 EPS03, July 17-23, 2003Lorenzo Vitale CP(t) asymmetries: fit technique CPV in mixing-decay interference direct CPV f ± (  t)  exp(–|  t|/  B ) ( 1 ± D (S sin(  m  t) - C cos(  m  t)) )  R B0B0 B0B0 f CP CP eigenvalue Amplitude ratio B 0 f cp /B 0 f cp B mixing D mis-tag dilution R time resolution Measured from data

16 EPS03, July 17-23, 2003Lorenzo Vitale 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.

17 EPS03, July 17-23, 2003Lorenzo Vitale D* + D* - Time dependent angular analysis CP even parameters CP odd parameters CP angular dilution factor: K = 1 – 2R ┴

18 EPS03, July 17-23, 2003Lorenzo Vitale Sensitivity in angular CP(t) analysis O 1D: Treat R  as dilution  2D: Use  tr  4D: Full angular analysis