We predict the matrix elements and resulting electron spectra for semileptonic meson decays using the quark potential model. Particular attention is paid to the high-energy electron end-point region in B decay since it is crucial to a determination of the b→u weak mixing angle. It is argued that in this region the usual inclusive (‘‘quark decay’’) calculations are unjustified and must be replaced by explicit sums over decays of the original meson into low-mass exclusive hadronic final states.

• Received 30 June 1988

DOI:https://doi.org/10.1103/PhysRevD.39.799