THEORETICAL UPDATE OF THE SEMILEPTONIC BRANCHING RATIO OF B-MESONS

We reconsider the prediction of the semileptonic branching ratio of B mesons, using the recent calculation [E. Bagan et al., Nucl. Phys. B 432 (1994) 3] of the radiative corrections with account for finite quark masses in nonleptonic decays and taking into account 1/m(b)(2) corrections. For the semileptonic branching ratio we obtain B-SL = (11.8 +/- 1.6)% using pole quark masses and B-SL = (11.0 +/- 1.9)% using running <($$)over bar>MS quark masses. The uncertainty is dominated by unknown higher order perturbative corrections. We conclude that the present accuracy of the theoretical analysis does not allow to state a significant disagreement with the experimental results, However, our re-analysis of the decay b --> ccs yields an increase of (35 +/- 11)% due to next-to-leading order corrections including mass dependent terms, which further emphasizes the problem of the average charm quark content of the final states in B decays.