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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) - PowerPoint PPT Presentation
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Hot Topics from BaBarFabrizio 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)
π K B0
000 K KB KK B
00
08/17/2004 F. Bianchi - ICHEP04 2
Direct CP Violation in π K B 0
Background-subtracted distribution for K+- (blue) and K-+ (red) decays
0
0
9
696
10
n B K
n B K
ππ
ππ
KK
KKCP nn
nnA
See Jinwei Wu talk in the CP session
009.0030.0133.0
/2s - E ΔE *B
Direct CP Violation @ 4.2
08/17/2004 F. Bianchi - ICHEP04 3
Study of KKB,KKB0000
KKB000 KKB
00
0Kb
tcu ,,
d d
dss
0K
b
u
dtcu ,, s
su
0K
K
R. Fleischer and S. Recksiegel, hep-ph/0408016
Pure b d penguin.
Can be correlated with B system.
08/17/2004 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 Ks
• |mKscand – mPDGKs| < 11.2 MeV (3.5 )
• Decay time significance > 5
08/17/2004 F. Bianchi - ICHEP04 5
Signal and sideband regions
•Two variables characterize a B candidate:
•We require:
•5.20 < mES < 5.29 GeV/c2
•|E| < 0.100 GeV ( )
•-0.115 < E < 0.075 GeV ( )
/2s - E ΔE *B *2
B*2BeamES pEm
000 KKB KKB
00
B background
signal
mES
(GeV/c2)
E
(GeV
)
08/17/2004 F. Bianchi - ICHEP04 6
Continuum Background Suppression
ContinuumBackground
Signal MCcut
Cosine of the angle between the sphericity axes of the B and of the rest of the event|cos(s)| < 0.8
Fisher Discriminant
i i
2*i
*i
*i )cos(θp1.27p0.600.53F
Signal MCContinuumBackground
Background from B decays is negligible
08/17/2004 F. Bianchi - ICHEP04 7
Likelihood Fit
PDF parameters determined from data and MC. Some free in the fit.
nsig and ACP from an Unbinned Likelihood with:
mES
E Fisher
c residual To separate K (only for Ks K+)
To discriminate against background
Cherenkov-anglemeasured by the DIRC
20441 Ks h+ candidates
1939 Ks Ks candidates
p(GeV/c)
c(r
ad
)
08/17/2004 F. Bianchi - ICHEP04 8
: results
@90%CL10 2.35
100.11)(1.46BR
31441n
6-
6-
sig
0.530.46
KKB,KKB0000
000 KKB
KKB00
σ 4.5:ceSignifican
100.13)(1.19BR
2.023n60.40
0.35
7.76.7sig
First observation of this mode
08/17/2004 F. Bianchi - ICHEP04 9
Search for D*sJ(2632)+
KD0
KD0
ηDs
Even
ts/1
0
MeV
/c2
Even
ts/5
M
eV
/c2
SELEX reported the discovery of a heavy state decaying to D+s and D0K+ 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/c2 m = M(K-K+)– M(K-+) MeV/c2
08/17/2004 F. Bianchi - ICHEP04 10
The Ds sample
BaBar: ~196,000 Ds in 125 fb-1 SELEX: ~550 Ds
m(K+K-+) GeV/c2
even
ts/1
.3 M
eV
/c2
m(K+K-+) GeV/c2
08/17/2004 F. Bianchi - ICHEP04 11
The sample ~3900 in Ds
+ sample at BaBar total inclusive at SELEX635087
even
ts/5
MeV
/c2
mGeV/c2 mMeV/c2
even
ts/4
MeV
/c2
08/17/2004 F. Bianchi - ICHEP04 12
Correlated production of Ds+
and
• There is 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: 75 1102 η) N(Ds
mGeV/c2m
GeV
/c2
m(K+K-+) GeV/c2
m(K+K-+) GeV/c2even
ts/2
.6 M
eV
/c2
even
ts/1
0 M
eV
/c2
08/17/2004 F. Bianchi - ICHEP04 13
Ds+mass spectrum
BaBar sees no D*sJ (2632)+ in 125 fb-1
Correlated Ds+
spectrum
after background
subtraction
ηDs
SELEX
2s GeV/c η)m(D
Even
ts/1
0
MeV
/c2
Even
ts/1
0
MeV
/c2
m = M(K+K-)– M(K+K-+) MeV/c2
08/17/2004 F. Bianchi - ICHEP04 14
D0K+ mass spectra
BaBar sees DsJ(2573)+ and
no DsJ(2632)+ in 125 fb-1
DsJ(2573)+
DsJ(2632)+
p* > 4.0 GeV/c
M(D0K+) GeV/c2
Even
ts/5
M
eV
/c2 Even
ts/5
M
eV
/c2
SELEX
m = M(K-K+)– M(K-+) MeV/c2
08/17/2004 F. Bianchi - ICHEP04 15
D*+Ks mass spectrum
BABAR sees Ds1 (2536)+ and
no DsJ (2632)+ in 125 fb-1
p* > 4.0 GeV/cDs1
(2536)+
DsJ
(2632)+
D*+Ks) – m(D*+) GeV/c2
Even
ts/2
.5
MeV
/c2
08/17/2004 F. Bianchi - ICHEP04 16
Summary
CL%90@10 2.35)KK BR(B -60
100.13)(1.19)KKBR(B 60.400.35
000
No evidence of D*sJ(2632)+ in Ds
+, D0K+, D*+Ks
009.0030.0133.0π KA Direct CP Violation in @ 4.2
First Observation @ 4.5
π K B 0
Backup Slides
08/17/2004 F. Bianchi - ICHEP04 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 cmeasured by the DIRC
• K- separation measured from D*+ D0 (D0 K- +)
08/17/2004 F. Bianchi - ICHEP04 19
PDF Parameterization
Variable Signal PDF Background PDF
mES Gaussian Argus
E Double Gaussian Poly2
Fisher Bifurcated Gaussian Double Gaussian
c residual Double Gaussian Double Gaussian