HADRONIC INVARIANT MASS DISCRIMINATES B-]U CONTRIBUTIONS IN SEMILEPTONIC B-DECAYS

We point out that directly measuring the invariant mass of final hadrons in B-meson semileptonic decays offers an alternative way to select b --> u transitions that is in principle more efficient than selecting the upper end of the lepton energy spectrum. In practice there are difficulties in determining precisely which hadrons are associated with a particular B decay, but with the advent of microvertex detectors and b-factories this approach may soon become feasible. It may also be possible to measure the hadronic invariant mass approximately via the lepton and neutrino momenta.