1. Hot Topics from BaBar Fabrizio Bianchi INFN, Torino (on behalf of the BaBar Collaboration) Direct CP Violation in (hep-ex/0407057) Observation of and search for (ICHEP 08/917) Search for the D * sJ (2632) + observed by SELEX (ICHEP 11/916)

2. 08/17/2004F. Bianchi - ICHEP042 Direct CP Violation in Background-subtracted distribution for K +  - (blue) and K -  + (red) decays See Jinwei Wu talk in the CP session Direct CP Violation @ 4.2 

3. 08/17/2004F. Bianchi - ICHEP043 Study of R. Fleischer and S. Recksiegel, hep-ph/0408016 Pure b d penguin. Can be correlated with B  system.

4. 08/17/2004F. Bianchi - ICHEP044 Data sample and B reconstruction Data Sample: 227 million B pairs collected at the Y(4S) energy 16 fb -1 of data recorded 40 MeV below the Y(4S) B candidates are reconstructed combining a K s candidate and a charged track or two K s candidates well reconstructed tracks within the DIRC acceptance K s candidates are reconstructed in the mode K s     |m K s cand – m PDGK s | < 11.2 MeV (3.5  ) Decay time significance > 5 

5. 08/17/2004F. Bianchi - ICHEP045 Signal and sideband regions Two variables characterize a B candidate: We require: 5.20 < m ES < 5.29 GeV/c 2 |  E| < 0.100 GeV ( ) -0.115 <  E < 0.075 GeV ( ) B background signal m ES (GeV/c 2 )  E (GeV)

6. 08/17/2004F. Bianchi - ICHEP046 Continuum Background Suppression Continuum Background Signal MC cut Cosine of the angle between the sphericity axes of the B and of the rest of the event |cos(  s )| < 0.8 Fisher Discriminant Signal MC Continuum Background Background from B decays is negligible

7. 08/17/2004F. Bianchi - ICHEP047 Likelihood Fit PDF parameters determined from data and MC. Some free in the fit. n sig and A CP from an Unbinned Likelihood with: m ES  E Fisher  c residual To separate K  (only for K s K + ) To discriminate against background Cherenkov-angle  measured by the DIRC 20441 K s h + candidates 1939 K s K s candidates p(GeV/c)  c (rad)

8. 08/17/2004F. Bianchi - ICHEP048 : results First observation of this mode

9. 08/17/2004F. Bianchi - ICHEP049 Search for D * sJ (2632) + Events/10 MeV/c 2 Events/5 MeV/c 2 SELEX reported the discovery of a heavy state decaying to D + s  and D 0 K + in 9.9 x 10 -9  - interactions on a set of thin foil targets of Cu or diamond collected at the 600 GeV hyperons beam at FNAL. (hep-ex/0406045, submitted to PRL)  m = M(K + K -    )  – M(K + K -  + ) MeV/c 2  m = M(K -   K + )  – M(K -  + ) MeV/c 2

10. 08/17/2004F. Bianchi - ICHEP0410 The D s sample BaBar: ~196,000 D s in 125 fb -1 SELEX: ~550 D s m(K + K -  + ) GeV/c 2 events/1.3 MeV/c 2 m(K + K -  + ) GeV/c 2

11. 08/17/2004F. Bianchi - ICHEP0411 The  sample ~3900  in D s + sample at BaBar total inclusive at SELEX events/5 MeV/c 2 m  GeV/c 2 m  MeV/c 2 events/4 MeV/c 2

12. 08/17/2004F. Bianchi - ICHEP0412 Correlated production of D s + and  There is  production in events with D s To check if they are correlated, we look for an excess in the overlap region. Excess after 2D sideband subtraction: m  GeV/c 2 m(K + K -  + ) GeV/c 2 events/2.6 MeV/c 2 events/10 MeV/c 2

13. 08/17/2004F. Bianchi - ICHEP0413 D s +  mass spectrum BaBar sees no D * sJ (2632) + in 125 fb -1 Correlated D s +  spectrum after background subtraction SELEX Events/10 MeV/c 2  m = M(K + K -    )  – M(K + K -  + ) MeV/c 2

14. 08/17/2004F. Bianchi - ICHEP0414 D 0 K + mass spectra BaBar sees D sJ (2573) + and no D sJ (2632) + in 125 fb -1 D sJ (2573) + D sJ (2632) + p * > 4.0 GeV/c M(D 0 K + ) GeV/c 2 Events/5 MeV/c 2 SELEX  m = M(K -   K + )  – M(K -  + ) MeV/c 2

15. 08/17/2004F. Bianchi - ICHEP0415 D *+ K s mass spectrum BABAR sees D s1 (2536) + and no D sJ (2632) + in 125 fb -1 p * > 4.0 GeV/cD s1 (2536) + D sJ (2632) +  D *+ K s ) – m(D *+ ) GeV/c 2 Events/2.5 MeV/c 2

16. 08/17/2004F. Bianchi - ICHEP0416 Summary No evidence of D * sJ (2632) + in D s + , D 0 K +, D *+ K s Direct CP Violation in @ 4.2  First Observation @ 4.5 

17. Backup Slides

18. 08/17/2004F. Bianchi - ICHEP0418 PID at BaBar At BaBar p of particles from 2-body B decays is between 1.5 and 4.5 GeV/c PID uses Cherenkov-angle  c measured by the DIRC K-  separation measured from D *+ D 0   (D 0 K -  + )

19. 08/17/2004F. Bianchi - ICHEP0419 PDF Parameterization VariableSignal PDFBackground PDF m ES GaussianArgus EE Double GaussianPoly2 FisherBifurcated GaussianDouble Gaussian  c residual Double Gaussian