Factorization in Color-Favored B Meson Decays to Charm

Abstract

Improved $B$ meson decay data have permitted more incisive tests of factorization predictions. A concurrent benefit is the ability to constrain the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$. Using a simultaneous fit to differential distributions $d Γ(\ob \to D^{*+} l^- \bar ν_l)/ dq^2$ measured by the CLEO and LEP Collaborations, the rates for the color-favored decays $\ob \to D^{(*)+} (π^-,ρ^-,a_1^-)$, and the rate for $\ob \to D^+ l^- \bar ν_l$, we find $|V_{cb}| = 0.0415 \pm 0.0022$. The slope of the universal Isgur-Wise form factor is described by a parameter found to be $\rs = 1.52 \pm 0.11$. Taking the $D_s$ meson decay constant from the world average of direct measurements, we predict satisfactorily the branching ratios for $\ob \to D^{(*)+} D_s^{(*)-}$. Ratios of helicity amplitudes for color-favored processes are also found to be in accord with predictions.

17 pages, LaTeX, 5 figures, submitted to Phys. Rev. D, revised version, semileptonic $B \to $D spectrum included in fit