Form factors of semileptonic decays of heavy mesons in the quark confinement model.

Abstract

We compute form factors of the semileptonic decay $B(D)\ensuremath{\rightarrow}\mathrm{Xl}\ensuremath{\nu}$ (we denote by $X$ the final pseudoscalar or vector state) within the quark confinement model. As ${M}_{Q}\ensuremath{\rightarrow}\ensuremath{\infty}$, one finds that the form factors of the $B\ensuremath{\rightarrow}D({D}^{*})e\ensuremath{\nu}$ decay state are expressed in terms of the universal function being dependent on the product of the four-velocities of initial and final heavy mesons in accordance with Isgur-Wise symmetry. At the same time, the form factors of decays with the final light state are found to be monopole functions except the axial-vector form factor ${A}_{1}(t)$, which goes to a constant in this limit. We compare our results obtained by explicit and asymptotic formulas with other approaches and available experimental data.