Semileptonic B-c(-) -> D(*0)l nu transition in three-point QCD sum rules and heavy quark effective theory with gluon condensate corrections

Taking into account the gluon condensate contributions, the form factors of the semileptonic B-c(-) -> D(*0)l nu transition with l = tau, e are calculated in the framework of the three-point QCD sum rules. The heavy quark effective theory limit of the form factors is also computed. The relevant total decay width as well as the branching ratio are evaluated and compared with the predictions of the other nonperturbative approaches.