The determination of $|V_{cb}|$ from semileptonic inclusive decay rates

Abstract

We report on the determination of $|V_{cb}|$ from the comparison of the semileptonic inclusive decay rates of B-- and D--mesons using the heavy quark symmetry of QCD. While the renormalization scale ambiguity does not allow for a reliable estimate of the quark masses, it almost cancels in the prediction for $|V_{cb}|$, which reads $|V_{cb}|({\tau }_B/1.49\mathrm{ps}{)}^{1/2}=0.036\pm 0.005$, where the error stems from the uncertainty in the kinetic energy of the heavy quark inside the meson, in the experimental branching ratios, in QCD input parameters, and from scale uncertainties. This talk is based on research work done in collaboration with Patricia Ball.

Comments: 4 pages and 2 figures, uses LaTeX espcrc2 documentstyle option (all necessary files included in an uuencoded compressed tar file). Talk given at the conference 'QCD94', Montpellier, France, 7-13 July 1994, to appear in Nucl. Phys. Proc. Suppl.