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

We compute form factors of the semileptonic decay B(D)→Xlν (we denote by X the final pseudoscalar or vector state) within the quark confinement model. As MQ→∞, one finds that the form factors of the B→D(D*)eν 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 A1(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