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