Influence of theB*resonance onB¯→πeν¯e

Abstract

In the chiral limit and as $m_b\to \infty$, the decay $\overline{B}\to {\pi }^{+}e{\overline{\nu }}_e$ would be dominated near zero pionic recoil by the effects of the $B^{*}$ resonance. We examine the influence of this mechanism on the $\overline{B}\to \mathrm{Xe}{\overline{\nu }}_e$ electron spectrum in the region near the end point which is important for the determination of the Kobayashi-Maskawa matrix element $V_{\mathrm{ub}}$.