1. Status report B  D 0 K  0 decay G.Calderini M.Carpinelli N.Neri BaBar Italia Capri 11 Apr 2003 INFN Pisa

2. Capri 11 Apr 2003 BaBar Italia2 Motivations of the analysis Possibility to measure the weak  angle. M. Gronau and D. Wyler, Phys. Lett. B 265, 172 (1991). Dalitz plot can help solving the 8-fold ambiguity of the  value. R.Aleksan et al. hep-ph/0209194 (Nov 2002) Measurement of the branching ratio of non resonant decay.

3. Capri 11 Apr 2003 BaBar Italia3 Extension to Wyler-Gronau method in B -  D 0 K - decays Measuring  through amplitude relationship  he decay amplitude varies in the Dalitz plot The Non Resonant decay is color allowed : larger interference.

4. Capri 11 Apr 2003 BaBar Italia4 Measurement of  Interference amplitudes for each region i of the Dalitz plot Relation among the number of measured events in each region i R.Aleksan et al. hep-ph/0209194 (Nov 2002) both color allowed for Non Resonant decay

5. Capri 11 Apr 2003 BaBar Italia5 Feynman diagrams (Non Res) W K+K+  D0D0 B+B+ W D0D0 K+K+  B+B+ The leading tree diagrams are both color allowed Interference amplitudes are both large b->c quark transition b->u quark transition leading diagram

6. Capri 11 Apr 2003 BaBar Italia6 MC Sample Releases 10.3.1x SP4  B + generic: 24.44 fb -1  B 0 generic: 14.87 fb -1  ccbar: 7.60 fb -1  uds: 3.63 fb -1  signal MC: D 0 K +  0 NR: 3000 Ev D *0 K + : 3000 Ev D 0 K *+ : 18000 Ev

7. Capri 11 Apr 2003 BaBar Italia7 List of candidates Release anal13b  B  list:BchToD0KPi0_Default,BchToD0barKPi0_D efault  D0 list: D0ToKPi_Loose into hadronic modes: K  K list : GTL  list : GTL K3 , K  0 will be added  D0 into CP modes KK, ,  s   will be added  K list: GTL     list  Pi0ToGGLoose

8. Capri 11 Apr 2003 BaBar Italia8 Selection cuts  Event shape: FoxWol < 0.3 |cos(  T )| < 0.75  |  E|<200MeV  P(  B+ 2 )>0.1 D0 selection K :KMicroTight doMass true P(  D0 2 )>0.01 |m D0 -m PDG |<3  K selection KMicroVeryTight p lab <2.75GeV  0 selection doMass true p lab >0.75GeV |m  0 -m PDG |<3   selection E lab >100MeV

9. Capri 11 Apr 2003 BaBar Italia9 Event Shape |COS(  T )|<0.75 FoxWol<0.3 BchB0ccbaruds sigNR keep65%60%20%22%75%

10. Capri 11 Apr 2003 BaBar Italia10 Work in Progress Fisher Discriminant (CLEO): 9 cones + cos  B + cos  T CLEO Fisher SIG continuum

11. Capri 11 Apr 2003 BaBar Italia11 D 0 Selection probD0>0.01 KMicroTight BchB0ccbaruds sigNR keep38%30%19%3.5%45%

12. Capri 11 Apr 2003 BaBar Italia12 Work in Progress  Added new info in the ntuple: D 0 flight length, beam-spot, primary vertex Time(ps) D 0 proper time distribution

13. Capri 11 Apr 2003 BaBar Italia13 Pi0 Selection BchB0ccbaruds sigNR keep25%34%28%55%86% P lab >0.75 GeV/c

14. Capri 11 Apr 2003 BaBar Italia14 Bkg composition  E distribution M ES distribution The number of events is scaled to 100 fb -1

15. Capri 11 Apr 2003 BaBar Italia15 BKG composition  Bch: 6 B decay not correctly reconstructed 12 combinatorial bkg events 5 false D0, 3 false Pi0, 4 other  B 0 : 1 B decay not correctly reconstructed 6 combinatorial bkg events 2 false D0, 2 false Pi0, 2 other  ccbar: 5 combinatorial events 1 false Pi0, 4 other B chargedB neutralccbarudsSigNR Event 18  4.2 Scale=4.09 [3.89-11.77] @90%CL Scale=6.72 [2.43-9.27] @90%CL Scale=13.16 <2.3 @90%CL Scale=27.50 30  5.5 Scale=1 Scaled Event 734765<6330 B -  D* 0  -  D 0  0   -  0 misid  lost  0 soft

16. Capri 11 Apr 2003 BaBar Italia16 Multiple candidates We found 1 candidate per event in the 3 sigma [M ES,  E] with present selection criteria. IF multiple candidate event is found we select the best candidate with the minimization of the  2 : This criteria in principle does not bias M ES,  E distribution.

17. Capri 11 Apr 2003 BaBar Italia17 Expected number of events  We can estimate the order of magnitude of NR BR assuming it equal to RES one: BR( D 0 K* +, K* +  K +   )  BR( D 0 K +   ) NR  1-210 -4 BR( D 0 K* + ) = 6.1 x 10 -4 [CLEO] We assume the BR= 1 10 -4  Efficiencies on signal MC after severe cuts with K  mode: 7% = 30 events  Adding K3  K    we can expect  3  times the number of events.

18. Capri 11 Apr 2003 BaBar Italia18 Work in Progress  Added new modes into the ntuple: K , K  , K3  KK,   SP5 signal MC: More MC signal NR produced with moose:  15000 events available (before we had 3000)  Started to write the BAD.  Discovered a bug in the Official Tag Bit for DKPi. Contacted the Breco convener and writing the new sequence for the next reprocessing.  Planning to run on data and MC filtering on an inclusive tag bit: D 0 + ntrkLoose>=3

19. Capri 11 Apr 2003 BaBar Italia19 Next step  Starting production on a consistent generic MC and DATA sample. BBbar, continuum, signal, cocktail D (*) K (*) Run1, Run2  Optimizing the Fisher discriminant approach.  Optimization of the cuts.  Starting cross checks using DATA-MC comparison.