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Hot Topics from BaBar Fabrizio Bianchi INFN, Torino (on behalf of the BaBar Collaboration)

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)

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Hot Topics from BaBar Fabrizio Bianchi INFN, Torino (on behalf of the BaBar Collaboration)

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  1. Hot Topics from BaBarFabrizio BianchiINFN, 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. Direct CP Violation in See Jinwei Wutalk in the CP session Background-subtracted distribution for K+p- (blue) and K-p+ (red) decays Direct CP Violation @ 4.2 s F. Bianchi - ICHEP04

  3. Study of Pure b d penguin. Can be correlated with B pp system. R. Fleischer and S. Recksiegel, hep-ph/0408016 F. Bianchi - ICHEP04

  4. 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 Ks candidate and a charged track or two Ks candidates • well reconstructed tracks within the DIRC acceptance • Ks candidates are reconstructed in the mode Ksp+ p- • |mKscand – mPDGKs| < 11.2 MeV (3.5 s) • Decay time significance > 5s F. Bianchi - ICHEP04

  5. signal B background Signal and sideband regions DE (GeV) • Two variables characterize a B candidate: • We require: • 5.20 < mES < 5.29 GeV/c2 • |DE| < 0.100 GeV ( ) • -0.115 < DE < 0.075 GeV ( ) mES (GeV/c2) F. Bianchi - ICHEP04

  6. Continuum Background Suppression Continuum Background Signal MC Continuum Background Signal MC cut Cosine of the angle between the sphericity axes of the B and of the rest of the event |cos(qs)| < 0.8 Fisher Discriminant Background from B decays is negligible F. Bianchi - ICHEP04

  7. Likelihood Fit 20441Ks h+ candidates 1939Ks Ks candidates nsig and ACP from an Unbinned Likelihood with: mES DE Fisher qc residual To separate K p (only for Ks K+) To discriminate against background qc(rad) Cherenkov-anglemeasured by the DIRC p(GeV/c) PDF parameters determined from data and MC. Some free in the fit. F. Bianchi - ICHEP04

  8. : results First observation of this mode F. Bianchi - ICHEP04

  9. Search for D*sJ(2632)+ SELEX reported the discovery of a heavy state decaying to D+sh and D0K+ in 9.9 x 10-9S- 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) Events/10 MeV/c2 Events/5 MeV/c2 Dm = M(K+K-p+h)– M(K+K-p+) MeV/c2 Dm = M(K-p+K+)– M(K-p+) MeV/c2 F. Bianchi - ICHEP04

  10. The Ds sample BaBar: ~196,000 Ds in 125 fb-1 SELEX: ~550 Ds events/1.3 MeV/c2 m(K+K-p+) GeV/c2 m(K+K-p+) GeV/c2 F. Bianchi - ICHEP04

  11. The h sample ~3900 h in Ds+sample at BaBartotal inclusive at SELEX events/5 MeV/c2 events/4 MeV/c2 m(gg) MeV/c2 m(gg) GeV/c2 F. Bianchi - ICHEP04

  12. Correlated production of Ds+ and h • There is h production in events with Ds • To check if they are correlated, we look for an excess in the overlap region. • Excess after 2D sideband subtraction: m(gg) GeV/c2 events/10 MeV/c2 m(K+K-p+) GeV/c2 m(gg) GeV/c2 events/2.6 MeV/c2 m(K+K-p+) GeV/c2 F. Bianchi - ICHEP04

  13. Ds+h mass spectrum Correlated Ds+ h spectrum after background subtraction Events/10 MeV/c2 SELEX Events/10 MeV/c2 Dm = M(K+K-p+h)– M(K+K-p+) MeV/c2 BaBar sees no D*sJ (2632)+ in 125 fb-1 F. Bianchi - ICHEP04

  14. D0K+ mass spectra DsJ(2632)+ DsJ(2573)+ Events/5 MeV/c2 SELEX Events/5 MeV/c2 Dm = M(K-p+K+)– M(K-p+) MeV/c2 M(D0K+) GeV/c2 BaBar sees DsJ(2573)+ and no DsJ(2632)+ in 125 fb-1 p* > 4.0 GeV/c F. Bianchi - ICHEP04

  15. D*+Ks mass spectrum Ds1 (2536)+ p* > 4.0 GeV/c DsJ (2632)+ Events/2.5 MeV/c2 BABARsees Ds1 (2536)+ and no DsJ (2632)+ in 125 fb-1 M(D*+Ks) – m(D*+) GeV/c2 F. Bianchi - ICHEP04

  16. Summary Direct CP Violation in @ 4.2 s First Observation @ 4.5 s No evidence of D*sJ(2632)+ in Ds+h, D0K+, D*+Ks F. Bianchi - ICHEP04

  17. Backup Slides

  18. 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 qcmeasured by the DIRC • K-p separation measured from D*+ D0p+ (D0 K-p+) F. Bianchi - ICHEP04

  19. PDF Parameterization F. Bianchi - ICHEP04

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