Moments of semileptonic B decay distributionsin the 1/m b expansion

Abstract

We report the OPE-based predictions for a number of lepton energy and hadronic mass moments in the inclusive semileptonic $B \to X_c \ell\nu$ decays with a lower cut on the charged lepton energy. We rely on the direct OPE approach where no expansion in the charm mass is employed and the theoretical input is a limited set of underlying OPE parameters including m b and m c . A Wilsonian treatment with a “hard” cutoff is applied using running low-scale masses $m_Q(\mu)$ and a kinetic expectation value $\mu_\pi^2(\mu)$ . This leaves for perturbative corrections only genuinely short-distance effects and makes them numerically small. Predictions are also given for the modified hadronic moments of the kinematic variable ${\cal N}_X^2$ which is a combination of M X 2 and E X . The measurement of such moments would allow a more reliable extraction to be made of higher-order non-perturbative heavy quark parameters from experiment.