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 $d\Gamma (\text{ob}\to D^{\ast +}{l}^{-}{\bar{\nu }}_l)/d{q}^2$ measured by the CLEO and LEP Collaborations, the rates for the color-favored decays $\text{ob}\to D^{(\ast )+}({\pi }^{-},{\rho }^{-},a_1^{-})$, and the rate for $\text{ob}\to D^{+}{l}^{-}{\bar{\nu }}_l$, 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 $\text{rs}=1.52\pm 0.11$. Taking the $D_s$ meson decay constant from the world average of direct measurements, we predict satisfactorily the branching ratios for $\text{ob}\to D^{(\ast )+}{D}_s^{(\ast )-}$. Ratios of helicity amplitudes for color-favored processes are also found to be in accord with predictions.

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