1. 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

2. 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

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

4. 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

5. 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| < GeV ( )
< DE < GeV ( )
mES (GeV/c2)
08/17/2004
F. Bianchi - ICHEP04

6. 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

7. 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

8. : results First observation of this mode 08/17/2004
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 10-9 S- interactions on a set of thin foil targets of Cu or diamond collected at the 600 GeV hyperons beam at FNAL. (hep-ex/ , submitted to PRL)
08/17/2004
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
BaBar: ~196,000 Ds in 125 fb SELEX: ~550 Ds
08/17/2004
F. Bianchi - ICHEP04

11. 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

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
08/17/2004
F. Bianchi - ICHEP04

13. 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

14. 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

15. 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

16. 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

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

19. 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