SemileptonicB→πdecay in a constituent quark-meson model

Abstract

We evaluate the form factors describing the exclusive decay $\stackrel{\ensuremath{\rightarrow}}{B}\ensuremath{\pi}l\ensuremath{\nu}$ by using a constituent quark-meson model based on an effective quark-meson Lagrangian. The model allows for an expansion in the pion momenta and we consider terms up to the first order in the pion field derivatives. We compute the leading terms in the soft pion limit and consider corrections to this limit.