Semileptonic B decays to excited charmed mesons

Abstract

Exclusive semileptonic B decays into excited charmed mesons are investigated at order ΛQCD/mQ in the heavy quark effective theory. Differential decay rates for each helicity state of the four lightest excited D mesons (D1, D2*, D0*, and D1*) are examined. At zero recoil, ΛQCD/mQ corrections to the matrix elements of the weak currents can be written in terms of the leading Isgur-Wise functions for the corresponding transition and meson mass splittings. A model independent prediction is found for the slope parameter of the decay rate into helicity zero D1 at zero recoil. The differential decay rates are predicted, including ΛQCD/mQ corrections with some model dependence away from zero recoil and including order αs corrections. Ratios of various exclusive branching ratios are computed. Matrix elements of the weak currents between B mesons and other excited charmed mesons are discussed at zero recoil to order ΛQCD/mQ. These amplitudes vanish at leading order, and can be written at order ΛQCD/mQ in terms of local matrix elements. Applications to B decay sum rules and factorization are presented.