Quark-binding effects in inclusive decays of heavy mesons

We present a new approach to the analysis of quark-binding effects in inclusive decays of heavy mesons within the relativistic dispersion quark model. Various differential distributions, such as electron energy spectrum, $q^2$- and $M_X$-distributions, are calculated in terms of the $B$ meson soft wave function which also determines long-distance effects in exclusive transition form factors. Using the quark-model parameters and the $B$ meson wave function previously determined from the description of the exclusive $b \to u$ transitions within the same dispersion approach, we provide numerical results on various distributions in the inclusive $B\to X_{c}l\nu$ decays.