Exclusive Semileptonic b u Decays at CLEO Sheldon Stone Syracuse University.
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Exclusive Semileptonic bu Decays at CLEO Sheldon Stone Syracuse University
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Transcript of Exclusive Semileptonic b u Decays at CLEO Sheldon Stone Syracuse University.
Exclusive Semileptonic bu Decays at CLEO
Sheldon StoneSyracuse University
CKM Workshop, Dec. 12-16, 2006 2
Introduction
Improved measurements of Bo -+ & -+ branching ratios and q2 dependences
Measurement of B+ + & evidence for B+ ’+
Analysis Uses Neutrino Reconstruction Extension of CLEO II/II.5 Analysis (PRD
68, 072003) by adding CLEO III data, 60% more data, total of ~14 fb-1
CKM Workshop, Dec. 12-16, 2006 3
Formalism in Pseudoscalar Decay
q2=(pB-pP
)2, kP is the P momentum in the B rest frame
2 22 3 2
2 324F
ub P
d B P GV k f q
dq
CKM Workshop, Dec. 12-16, 2006 4
Formalism in Vector Decay
WL is the between the + direction in the W rest frame & the W direction in the B rest frame
q2=(pB-pV)2, kV is the V momentum in the B
rest frame
2 22 2 2
2
2 322
0
1 cos 1 cos2 2
cos 128sin
W WF B Vub
WW
H Hd B V G M k q
Vdq d
H
2 2)1
22 2 2
0 1 22
2 /( )
11 4
2
B V B V
VBV
V B V B
H A q M k V q M m
mMH y A q k A q
m M m My
CKM Workshop, Dec. 12-16, 2006 5
p Resolution
p GeV/c
Neutrino Reconstruction
Estimate 4-vector using pmiss pCM-pvisible & Emiss ECM-Evisible
Require in general net charge of 0, (in 0- modes also use ±1)
Require MM2 ~0 (MM2/2Emiss <0.5 GeV)
Require Spherical events Identify e+ or + with p>1 GeV/c (reject
events with >1 lepton) Form E=Ehad+E-E-Ebeam & Mh
2=Ebeam2-(phad+p+p)2
~0.1 GeV/c
CKM Workshop, Dec. 12-16, 2006 6
Measurement Technique Vector state sensitive to
cosWL
Binning B in q2 & cosWL
bins drastically reduces model dependence of
branching ratio determination B in q2 bins B in all phase space B’ in all phase space
Rat
io C
os<
0 /
Co
s>0
q2 GeV2Ball04, Mel, UKQCD, ISGW2
B
CKM Workshop, Dec. 12-16, 2006 7
Expectations from Simulation
Use binned log likelihood method simultaneously in all modes and bins
Use isospin constraints & efficiency matrix
Signal peaks here
Backgrounds peak here
CKM Workshop, Dec. 12-16, 2006 8
Fit Components
Backgrounds Signals
BXu
other
Continuum(absolutely normalized)
B Signal
±0 XFeed
, 0 XFeed
Data
BXc
Eve
nts
/7.5
MeV
/c2
Mhlv GeV/c2
Fake Lepton(absolutely normalized,
very small)
, XFeed(very small)
CKM Workshop, Dec. 12-16, 2006 9
Results from Fit (Summed)
Mhlv GeV/c2Mhlv GeV/c2Mhlv GeV/c2Mhlv GeV/c2Eve
nts
/7.5
MeV
/c2
Eve
nts
/100
MeV
/c2
GeV GeV GeV GeV
+o +oo Mh Distribution -0.15< <0.25 GeV
Distribution 5.265< Mh < 5.28 GeV
CKM Workshop, Dec. 12-16, 2006 10
Systematic ErrorsL
arg
est
So
urc
e O
f S
yste
mat
ic U
nce
rtai
nty
CKM Workshop, Dec. 12-16, 2006 11
B
10-4
/Ge
V2
q2 GeV2 q2 GeV2
HPQCD 04 Prediction
Ball 04 Prediction
coswl<0coswl>0
B
10-4
/Ge
V2
Results
B(B)= (1.370.150.120.01)10-
4
B(B)= (2.930.370.390.04)10-4
B(B++) = (0.440.230.110.00)x10-4, <1.0110-4 @90% clB(B++) = (2.660.800.570.04)x10-4, 3 effect(B++)/(B++)>2.5 @90% clTheory without color singlet has B(B++) =0.4x10-4, B(B++) =0.2x10-4, inconsistent with data
CKM Workshop, Dec. 12-16, 2006 12
#BB106
B(B) 104
CLEO Oct 2006
15.4 1.370.15stat0.12
sys
BABARJul 2006
227.0 1.440.08stat0.10sys
BELLEJun 2006
275.0 1.380.19stat0.14sys
HFAGichep06
Avg 1.370.06stat0.06
sys
B(B)
B Comparisons•Competitive with B factories due tohigher efficiencies atsymmetric machine
CKM Workshop, Dec. 12-16, 2006 13
B Comparisons
#N106
B(B) 10-4
CLEOOct 2006
15.4 2.930.37stat0.39sys
BABARSep 2005
83.0 2.140.21stat0.56sy
s
BELLEJun 2006
275.0 2.170.54stat0.32sy
s
B(B)
CKM Workshop, Dec. 12-16, 2006 14
Measurement of |Vub|
•We use our measurement for B for q2 > 16 GeV2
•And recent results from unquenched lattice calculation: HPQCD collaboration (Gulez, et al, PRD 73, 074502, 2006).
CLEO (2006):
BABAR (2006):
BELLE (2006):
Note that the theoretical error dominates
0.6 3ub 0.4V 4.3 0.4 0.2 x10
0.6 3ub 0.4V 4.1 0.2 0.2 x10
0.6 3ub 0.4V 4.0 0.5 0.2 x10
CKM Workshop, Dec. 12-16, 2006 15
Conclusions Using reconstruction CLEO measured Branching
ratios for B→(, , ’) & an upper limit for B→ B(B)= (1.37 0.150.12 0.01)10-4
B(B)= (2.93 0.37 0.39 0.04) 10-4
B(B ’)= (2.66 0.80 0.57 0.04) 10-4
“3 evidence for” B(B) < 1.0110-4 @ 90% C.L.
Extracted |Vub| using q2>16 GeV2 and HPQCD prediction:
0.6 3ub 0.4V 4.3 0.4 0.2 x10
CKM Workshop, Dec. 12-16, 2006 16
A Tribute to Bernie Gittelman
1932-Nov. 25, 2006 A hero of flavor physics Pioneered e- storage
rings at SLAC First to measure B
semileptonic decays Led CLEO II project
