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 π K B 0 0 0 0 K K B K K B 0 0
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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) - 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