Title

Measurement of the B̄→D*lν̄ branching fractions and -Vcb-

Authors

B. Barish, California Institute of Technology
M. Chadha, California Institute of Technology
S. Chan, California Institute of Technology
D. F. Cowen, California Institute of Technology
G. Eigen, California Institute of Technology
J. S. Miller, California Institute of Technology
C. O'Grady, California Institute of Technology
J. Urheim, California Institute of Technology
A. J. Weinstein, California Institute of Technology
D. Acosta, University of California, San Diego
M. Athanas, University of California, San Diego
G. Masek, University of California, San Diego
H. P. Paar, University of California, San Diego
J. Gronberg, University of California, Santa Barbara
R. Kutschke, University of California, Santa Barbara
S. Menary, University of California, Santa Barbara
R. J. Morrison, University of California, Santa Barbara
S. Nakanishi, University of California, Santa Barbara
H. N. Nelson, University of California, Santa Barbara
T. K. Nelson, University of California, Santa Barbara
C. Qiao, University of California, Santa Barbara
J. D. Richman, University of California, Santa Barbara
A. Ryd, University of California, Santa Barbara
H. Tajima, University of California, Santa Barbara
D. Sperka, University of California, Santa Barbara
M. S. Witherell, University of California, Santa Barbara
M. Procario, Carnegie Mellon University
R. Balest, University of Colorado Boulder
K. Cho, University of Colorado Boulder
M. Daoudi, University of Colorado Boulder
W. T. Ford, University of Colorado Boulder
D. R. Johnson, University of Colorado Boulder
K. Lingel, University of Colorado Boulder

Document Type

Article

Publication Date

1-1-1995

Abstract

We study the exclusive semileptonic B meson decays B-→D*0l-ν̄ and B̄0→D*+l-ν̄ using data collected with the CLEO II detector at the Cornell Electron-positron Storage Ring (CESR). We present measurements of the branching fractions scrB(B̄0→D*+l-ν̄)= (0.5/f00)[4.49±0.32(stat.)±0.39 (syst.)]% and scrB(B-→D*0l-(ν̄)= (0.5/f+-)[5.13±0.54 (stat) ±0.64 (syst)]%, where f00 and f+- are the neutral and charged B meson production fractions at the Υ(4S) resonance, respectively. Assuming isospin invariance and taking the ratio of charged to neutral B meson lifetimes measured at higher energy machines, we determine the ratio f+-/f00=1.04±0.13 (stat) ±0.12 (syst) ±0.10 (lifetime); further assuming f+-+f00=1 we also determine the partial width Γ(B̄→D*lν̄)=[29.9±1.9 (stat) ±2.7 (syst.) ±2.0 (lifetime)] ns-1 (independent of f+-/f00). From this partial width we calculate B̄→D*lν̄ branching fractions that do not depend on f+-/f00 or the individual B lifetimes, but only on the charged to neutral B lifetime ratio. The product of the CKM matrix element -Vcb- times the normalization of the decay form factor at the point of no recoil of the D* meson, scrF(y=1), is determined from a linear fit to the combined differential decay rate of the exclusive B̄→D*lν̄ decays: -Vcb-scrF(1)=0.0351±0.0019 (stat) ±0.0018 (syst) ±0.0008 (lifetime). The value for -Vcb- is extracted using theoretical calculations of the form factor normalization. © 1995 The American Physical Society.

Publication Name

Physical Review D

Volume Number

51

First Page

1014

Last Page

1033

Issue Number

3

DOI

10.1103/PhysRevD.51.1014

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