$|V_{ub}|$ from exclusive $B$ and $D$ decays

Abstract

We propose a model-independent method to determine the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{ub}|$ from exclusive $B$ and $D$ decays. Combining information obtainable from $B\to ρ\ell\barν_\ell$, $B\to K^*ν\barν$, $D\to ρ\bar\ellν_\ell$ and $D\to K^*\bar\ellν_\ell$, a determination of $|V_{ub}|$ is possible, with an uncertainty from theory of around 10\%. Theoretical uncertainties in the $B\to K^*\ell\bar\ell$ decay rate are discussed.