Dependence of the Form Factors of $B\to \pi \ell \nu$ on the Heavy Quark Mass

Abstract

We use QCD sum rules to analyze the semileptonic transition $B\to \pi \ell \nu$ in the limit $m_b\to \infty$. We derive the dependence of the form factor $F_1(0)$ on the heavy quark mass, which is compatible with the expected dependence for the simple pole model of $F_1(q^2)$.

Comments: Latex, 10 pages, 2 figures (PostScript files included), BARI-TH/93-163, DSF-T-93/45, INFN-NA-IV-93/45