Rare and Hadronic B decays
in BABAR
L.Lista
INFN Sezione di Napoli
Luca Lista
Outline
• Charmonium decays
 Inclusive
 Exclusive
 J/ K* angular analysis
•
•
•
•
Open Charm
2-body hadronic decays
quasi 2-body decays
Radiative penguin
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Inclusive Charmonium Decays
Lepton identification
• B-counting:
off
N MH
N  ( 4 S )  N HM  N  off 
N 
• Correct by (4S)
• 1.6% sys. Error
• 22,700,000 BB
events
• Bremstrahlung-recovery for electrons
• Background rejection:
 At least 3 tracks, Etot > 4.5 GeV
 Ratio of 2nd to 0th Fox-Wolfram moment R2 < 0.5
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Inclusive Charmonium: J/
J/ l+l, l= e, 
p*J/ < 2 GeV/c
• Inclusive branching ratio:
 Br(BJ/X)
= (1.0440.013 0.028)  10-2
 Br(BJ/X dir.) = (0.7890.010 0.034)  10-2
• J/ momentum distribution measured
 Y(4S) system = B system  250 MeV
• Polarization -0.4240.023 (-1 = longitudinal)
• Signal from continuum subtracted ( …)
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•
J/ production in continuum
Not a B decay, but a new BaBar result…
• First observation of J/ production in
continuum
•
•
•
 Rejection of BB (p*>2 GeV/c)
 Rejection of ISR (Ntracks, Etot, R2)
Angular distribution: 1+A cos2q*
A (all E*)
= 0.250.19
A (p*>3.5 GeV) = 0.620.39
mode
resonance
p* cut (GeV/c)
yield

ee

ee
on
on
off
off
>2
>2
-
87952
79962
15625
12126
e e
+ 
 Color singles: A  –0.8,  2.8 pb
 NDQCD (c.o): 0.6<A<1.0,  0.8 pb
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 J /X
 2.52  0.21  0.21 pb
B ( 4 S ) J /X  4.3 10 4 (90%C.L.)
Inclusive Charmonium: (2S)
(2S) l+l, J/+
• Br( B (2S) X ) =
(0.2750.020 0.029) 10-2
• (2S)  l+l branching ratio
p* < 1.6 GeV/c
• Assuming PDG values for
(2S)  J/+
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Inclusive Charmonium: c
c2 (?)
c2 (?)
• Br(B c1 X)
= (0.378 0.034 0.026)10-2
• Br(B c1 X dir.) = (0.353 0.034 0.024)10-2
• Br(B c2 X)
= (0.137 0.058 0.012)10-2
< 0.2110-2 @ 90% C.L.
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Exclusive decays
• Several CP channels
Example: BD0
• Direct CP asymmetry
• Kinematics selection:
 Energy substituted mass
mES
E (GeV)
 sin2b
s

 pB2 ,cm
4
• Independent on particle
mass hypotheses
 Energy difference
in the center of mass
s
E  E B 
2
mES (GeV/c2)
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BJ/K0S
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BJ/K0L
• KL reconstructed as neutral
deposit in the IFR or E.M.
Calorimeter
• 1.4 < p*J/ < 2.0 GeV/c
• No momentum
measurement
•
E is measured
assuming the mB
mass constraint
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Selected channels
First observation
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Branching rations results
Mode
Br (10-4)
B0J/0
0.20.060.03
B0J/K*0
12.40.50.8
B+J/K*+
13.70.91.1
B+J/K+
10.00.30.5
B0J/K0(KL)
6.80.80.8
B0J/K0(KS00)
9.61.50.7
B0J/K0(KS+)
8.30.50.6
B0c1K*0
4.81.50.9
B+c1K+
5.11.41.3
B+(2S)K+
6.10.50.8
B0(2S)K0
6.51.01.1
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BaBar compared to PDG 2000
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J/+ / J/K+
• Cabibbo and color suppressed tree diagram
 possible CP asymmetry from penguin contribution
• Unbinned maximum likelihood fit based on kinematical
variables:
• Br(B+J/K+)/(B+J/+) =(3.910.78 0.19)10-2
( 5.2  2.4 ) %
( 5.0 +1.9  0.1 ) %
CLEO
CDF
PDG
BaBar
1.7
( 5.1  1.4 ) %
0
2
4
6
Br(B+ to JpsiPi+) / Br(B+ to Jpsi K+)
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8
10
J/ K* angular analysis
Channels without 0
Channels with 0
J/ rest frame
K* decay plane
• f (cosqtr, cosqK*, tr) = f1 |A0|2 + f2 |A|||2 + f3|A|2
f4 Im(A||* A) + f5 Re (A0* A||) + f6 Im (A0* A)
|A|2 + |A|||2 + |A0|2 = 1
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J/ K* angular analysis
|A|2 = 0.1600.032 0.014
CP odd, P wave
|A|||2 = 0.2430.034 0.017
CP even, S+D wave
|A0|2 = 0.5970.028 0.024
CP even, S+D wave
 = arg(A/A0)=0.170.16 0.07
|| = arg(A|| /A0)=2.500.20 0.08
Indication of FSI
(a) Raw measurement
(b) Acceptance correction
(c) “ “ + mES fit
(d) “ “ + (Self) Feed Across
CP asymmetry dilution factor:
D = 1 – 2 |A|2 = 0.680.10
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BD*+, D*+r
• May exhibit small CP asymmetries
• Potential for sin(2b+g) and
• Reconstruct the decay chains:
B D 
0
*+
B 0  D*+ r 

  0
D 0 +
D 0 +
K  +
K  +
• B reconstruction efficiencies estimated with MC
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BD*+
Br(BD*+) = (2.9 ± 0.3 ± 0.3 )  10-3
PDG: (2.76 ± 0.21)  10-3
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BD*+r
Br(BD*+r) = (11.2 ± 1.1 ± 2.5 )  10- 3
PDG: (6.8 ± 3.4)  10-3
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B  D*+D*
• Independent measurement of sin2b
• D*+D+0, D0+
 D0K+, K+0, K++, KS+
 D+ K++, KS+, KK++
• B decays with two 0 are not used
 High background, low branching fraction
• Many possible combinations in the same event.
Chosen the one which minimizes:
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B  D*+D*
Br(BD*+D*-) = (8.0 1.6  1.2)10-4
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B  D*D(*)K
•
•
•
•
•
•
•
•
bccs transition
D*+ D0+;
D*0 D00
D*0 D0g
D0 K-+,
D0 K-+0
D0 K-+-+;
D+ K-++;
B+ (all modes)
NS = 11715
• Br(B0 D*+D0K+) = (0.280.070.05)10-2
• Br(B0 D*+D*0K+) = (0.680.170.17)10-2
• Br(B+ D*+D*K+) = (0.340.160.11)10-2
 First observation of non-charmonium
color suppressed mode
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B0 (all modes)
NS = 18021
B+ D*+D*K+
NS = 8.23.5
Charmless Hadronic Decays
• Physics motivations
Cabibbo suppressed
Vud(s)
B0
b
{d
Vub W

u
d(s)
u
d
}  (K )
}


+
Penguin diagram
B0
b
{d
W Vtd(s)
Vtb
t
• Significant penguin
contribution
• Direct CP violation
studies
• Measurement of  from
time-dependent
asymmetry + isospin
analysis
}
}
u
(K)
d(s)
u
+
d
• Possible field for new
physics…
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Identifying K and 
• Particle identification in the DIRC
D*+D0, D0K-+ control sample
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Background Rejection
• Continuum events rejection
 Fisher discriminator on event shape
 Thrust axis (B vs rest of event)
• Background control samples
 E sidebands
 Off-resonance data
 D*+D0, D0K+ control sample
background
 D0+
 on reson.
mES<5.26
signal
background
signal
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Two Body Charged Modes
•
Cut based selection
Bh+h
+
UML Fit results
Mode Yeld, significance
Branching ratio
K+
16917+12-17, 15.8
(16.71.6+1.2-1.7)10–6
 + 
41107, 4.7
(4.11.00.7)10–6
K+
K+K
K+K 8.2+7.8–6.43.3, 1.3
<2.510–6 (90%C.L.)
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Two Body Charged + Neutral Modes
•
Cut based projections
B0h+
0+
UML Fit results
Mode Yeld, significance
Branching ratio
0 +
37+15-13, 3.4
(5.1+2.0-1.8 0.8)10–6
0K+
75+14-13, 8.0
(10.8+2.1-1.9 +1.0-1.2 )10–6
0K+
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BK0h+, K00
Cut based projections
K00
K0+
Mode
Yield, significance
Branching ratio
K0+
59+11-10, 9.8
(18.2+3.3-3.0 +1.6-2.0)10–6
K0K+
0 (< 8), 0
<2.610–6 (90%C.L.)
K00
17.9+6.8-5.8, 4.5
(8.2+3.1-2.7 +1.1-1.2)10–6
K0K+
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Charge Asymmetries
• K+
• K+0
• K+
A = - 0.190.100.03
[ -0.35, -0.03 ], 90%C.L.
A = 0.000.180.04
[ -0.30, +0.30 ], 90%C.L.
A = - 0.210.180.03
[ -0.51, +0.09 ], 90%C.L.
• All asymmetries compatible with 0 within
current errors
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Quasi 2-body and 3-body decays
B+h+
B0K0
B+K+
B0K0
< 24  10-6 ( 90% C.L. )
< 14  10-6
( 62  18  8 )  10-6
< 112  10-6
B0K*0 +
B+r0K+
B+r0+
B+K++
B+++
B0r
< 28  10-6
< 39  10-6
< 39  10-6
< 54  10-6
< 22  10-6
( 49  13+6-5 )  10-6
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BK, BK*
• Penguin dominated
• Measure of sin2b
B+K+
B0 K0
B+ K*+
B0 K*0
B0 +
= (7.7+1.6-1.40.8)  10-6
= (8.1+3.1-2.50.8)  10-6
= (9.7+4.2-3.41.7)  10-6
= (8.6+2.8-2.41.1)  10-6
< 1.4  10-6 (90% C.L.)
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B  K*g
Signal:
• Sensitive to top quark
couplings
 CKM matrix elements
Vtd,Vts
• Sensitive to New
Physics
 SUSY, Charged Higgs
• No CP asymmetry in the
Standard Model
 Possible sources
beyond SM
B0  K*0g,
K*0  K+Backgrounds:
e+e-  qq g
e+e-  qq  X 0
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B  K*g: yield and branching ratio
• Nsignal = 139.2  13.1 events
• Br(B0  K*0g) = (4.39  0.41)  10-5
•
•
•
•
Br(B  K+e+e-)
Br(B  K++-)
Br(B  K*0e+e-)
Br(B  K*0+-)
< 12.8  10-6
< 8.3  10-6
< 24.7  10-6
< 25.7  10-6 (90% C.L.)
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B  K*g: CP asymmetry
• K*0 K+
• N(B0) = 72.1  9.4 events
• N(B0) = 67.2  9.1 events
K*0 g
-
• ACP = -0.035  0.09
K*0 g
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bsg, B  gg
• Semi-exclusive study
 Sum of exclusive modes
K+n (n=1,2,3)
mES for 0.6 <mhad < 2.0 GeV
668  53 events
• B(B0gg) < 1.94 x 10-6 90% C.L.
• PDG: B(B0 gg) < 3.9 x 10-5 90% C.L. (from L3)
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Conclusions
• Many branching ratios have been measured in
BaBar
• Some are newly observed signals
• Potential for more CP violation studies
• More statistics will permit to measure CP
asymmetries
• Stay tuned!
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