On Production of d and D* Mesons in B Meson Decays

The decays B..-->..D*e..nu.. and B..-->..De..nu.. are considered. It is shown that in a certain theoretical limit, the probability of decays of this type may be reliably calculated, and these two decay channels exactly saturate the semileptonic width. Real B and D mesons lie in a region rather close to this limit. The probability for the decay B..-->..D*e..nu.. may be calculated for soft D* mesons with an accuracy of approx.10%. Total branching ratios of B..-->..D*e..nu.. and B..-->..De..nu.. are estimated within a factor of 1.5 to be, respectively, approx.8% and approx.2%. The proposed approach can be used for a rough estimate of nonleptonic decay rates of B mesons involving D or D* in the final state.