Study of B decays to Charmonium with BaBar

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Study of B decays to Charmonium with BaBar
Giovanni Calderini (SLAC) for the BaBar
Collaboration HEP 2001, Budapest
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Data Sample and B Counting
Analyses based on data collected in 1999-2000
BaBar
20.7 fb-1 on peak 2.6 fb-1 off-peak
Subtract the continuum contribution using
off-peak running, normalized by the number of
observed events
mm-
Procedure yields 22.7 x 106 BB pairs
For branching fraction extraction, assume
B0B0BB- 11
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J/y, y(2s) and cc are reconstructed in final
states containing leptons
Tight particle ID selection (high e, low mis-ID)
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Inclusive Charmonium Production
Yield 15739 ? 177
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P measured in Y(4s) frame
J/y from B decays below 2 GeV/c
Used to separate from prompt J/y (continuum)
Sum of ee mm
Data
Difference between
ee and mm
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J/y Helicity
Helicity Angle between J/y flight direction in
the Y(4s) frame and positive lepton in J/y rest
frame.
Fit u cosQH distribution to extract J/y
polarization
a -0.424 ? 0.023

• 1 transverse

a 0 unpolarized
a -1 longitudinal
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Inclusive Charmonium Production B y (2s)
X
p lt 1.6 GeV/c
y(2s) ee-
y(2s) mm-
Yield 552 ? 50
Yield 437 ? 44
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y(2s) J/y pp-
J/y mm-
Yield 405 ? 37
Yield 400 ? 34
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Inclusive Charmonium Production cc1 (cc2)
g J/y
X
X
B
Yield 471 ? 71
cc1
Yield 545 ? 60
cc2
(?)
104 ? 56
86 ? 59
mm-
ee-
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Exclusive Charmonium Modes
Combine a Ks , KL , K?, K or p0 with
charmonium meson to build two-body decays.
Kinematic variables DE in center of mass
and beam substituted mass (Mes)
B J/y Ks (pp-)
golden CP channel
Yield 265.5 ? 2.9
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B J/y Ks (p0p0)
B J/y pp-
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More B0 modes
J/y K0
J/y p0
Yield 13.6 ? 0.9
Yield 594.8 ? 8.5
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A different technique J/y KL
(also a CP mode)
KL direction measured from EMC and/or IFR
Data
Use mB constraint to determine KL energy
J/y signal MC
Background
Yield 183 ? 14
Veto events reconstructed as signal in other
exclusive modes
Signal purity 47
Signal yield 183 ? 14 events
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Similar signal for B modes
J/y K (Kp0)
J/y K
J/y K (Ksp)
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B J/y K
B J/y p
Different analysis based on unbinned
maximium likelihood fit
Separation provided by kinematics
B J/y p
)
(
3.91 ? 0.78 ? 0.19
B J/y K
Still dominated by statistical uncertainty
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B decays involving y(2s)
B y(2s) Ks
B y(2s) K
Also for the exclusive modes, y(2s)
reconstructed in
y(2s)
ee- , mm- , J/y pp-
Yield 56.0 ? 3.4
Yield 207.3 ? 6.2
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B decays involving cc
Yield 145.1 ? 7.2
Yield 32.6 ? 6.0
Yield 26.1 ? 2.5
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Preliminary study of B decays to hc K
hc
KK-KK-
hc
KK-p0
hc
KsKp
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Exclusive Charmonium Modes results
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Summary
We have measured inclusive charmonium production
in B decays
We have measured the Branching Fractions for
several exclusive B decays to charmonium final
states. Most of these measurements are more
precise than the present PDG values.
More statistics will permit to improve the
current measurements and to access more rare
channels