Hot Topics from BaBar Fabrizio Bianchi INFN, Torino (on behalf of the BaBar Collaboration) Direct CP Violation in Observation of and search for Search for the D*sJ(2632)+ observed by SELEX

Direct CP Violation in See Jinwei Wu talk in the CP session Background-subtracted distribution for K+p- (blue) and K-p+ (red) decays 08/17/2004 F. Bianchi - ICHEP04

Study of is a pure penguin (same as in B p p) has a penguin and annihilation amplitudes 08/17/2004 F. Bianchi - ICHEP04

Data sample and B reconstruction 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 Ks p+ p- |mKscand – mPDGKs| < 11.2 MeV (3.5 s) Decay time significance > 5s 08/17/2004 F. Bianchi - ICHEP04

Signal and sideband regions B background signal 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) 08/17/2004 F. Bianchi - ICHEP04

Continuum Background Suppression Signal MC Continuum Background Signal MC cut Cosine of the angle between the thrust axes of the B and of the rest of the event |cos(qs)| < 0.8 Fisher Discriminant Background from B decays is negligible 08/17/2004 F. Bianchi - ICHEP04

Likelihood Fit Cherenkov-angle measured by the DIRC 20441 Ks h+ candidates 1939 Ks 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-angle measured by the DIRC p(GeV/c) PDF parameters determined from data and MC. Some free in the fit. 08/17/2004 F. Bianchi - ICHEP04

: results First observation of this mode 08/17/2004 F. Bianchi - ICHEP04

Search for D*sJ(2632)+ SELEX reported the discovery of a heavy state decaying to D+sh and D0K+ in 9.9 x 10-9 S- 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) 08/17/2004 F. Bianchi - ICHEP04

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 BaBar: ~196,000 Ds in 125 fb-1 SELEX: ~550 Ds 08/17/2004 F. Bianchi - ICHEP04

The h sample ~3900 h in Ds+ sample at BaBar total inclusive at SELEX events/5 MeV/c2 events/4 MeV/c2 m(gg) MeV/c2 m(gg) GeV/c2 08/17/2004 F. Bianchi - ICHEP04

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 08/17/2004 F. Bianchi - ICHEP04

Correlated Ds+ h spectrum after background subtraction Ds+h mass spectrum Correlated Ds+ h spectrum after background subtraction Events/10 MeV/c2 SELEX Events/10 MeV/c2 BaBar sees no D*sJ (2632)+ in 125 fb-1 08/17/2004 F. Bianchi - ICHEP04

D0K+ mass spectra DsJ(2632)+ DsJ(2573)+ BaBar sees DsJ(2573)+ and Events/5 MeV/c2 SELEX Events/5 MeV/c2 M(D0K+) GeV/c2 BaBar sees DsJ(2573)+ and no DsJ(2632)+ in 125 fb-1 p* > 4.0 GeV/c 08/17/2004 F. Bianchi - ICHEP04

D*+Ks mass spectrum Ds1 (2536)+ p* > 4.0 GeV/c DsJ (2632)+ Events/2.5 MeV/c2 BABAR sees Ds1 (2536)+ and no DsJ (2632)+ in 125 fb-1 M(D*+Ks) – m(D*+) GeV/c2 08/17/2004 F. Bianchi - ICHEP04

Summary Direct CP Violation in First Observation @4.5 s No evidence of D*sJ(2632)+ in Ds+h, D0K+, D*+Ks 08/17/2004 F. Bianchi - ICHEP04

Backup Slides

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 qc measured by the DIRC K-p separation measured from D*+ D0 p+ (D0 K- p+) 08/17/2004 F. Bianchi - ICHEP04

PDF Parameterization Variable Signal PDF Background PDF mES Gaussian Argus DE Double Gaussian Poly2 Fisher Bifurcated Gaussian qc residual 08/17/2004 F. Bianchi - ICHEP04