Semileptonic b -> (d)over-bar transition in a nuclear medium

Abstract

We study the semileptonic tree-level B -> (D) over bar transition in the framework of QCD sum rules in a nuclear medium. In particular, we calculate the in-medium form factors entering the transition matrix elements defining this decay channel. It is found that the interactions of the participating particles with the medium lead to a considerable suppression in the branching ratio compared to the vacuum.