Lepton asymmetry measurements in B̄→D*l-ν̄l and implications for V-A and the form factors

California Institute of Technology
University of Oklahoma
San Diego University of California
Syracuse University
University of Minnesota Twin Cities
Santa Barbara University of California
Carnegie Mellon University
University of Rochester
Southern Methodist University
Lawrence University of Kansas
University of Florida
Ithaca College
Harvard University
University at Albany State University of New York
Cornell University
Purdue University
Ohio State University
Vanderbilt University
University of Colorado at Boulder

Abstract

We present a measurement of the lepton decay asymmetry Afb in the reaction B¯→D*l−ν¯l using data collected with the CLEO II detector at the Cornell Electron Storage Ring (CESR). The value of Afb confirms that the chirality of the weak interaction is predominantly left-handed in b→c transitions as expected in the standard model, if it is assumed that the lepton current is also left-handed. Using Afb and the previously determined branching ratio, q2 distribution, and D* polarization, we obtain the first measurement of the form-factor ratios that are used to describe this semileptonic decay.