Excited charm mesons in semileptonic B-bar decay and their contributions to a Bjorken sum rule.

Abstract

It has recently been shown that hadrons containing a single heavy quark exhibit a new flavor-spin symmetry of QCD. We exploit this symmetry to obtain model-independent predictions for the 14 form factors in weak decays from the ground-state pseudoscalar meson {ital P}{sub {ital Q}{ital i}} of a heavy quark {ital Q}{sub {ital i}} to the low-lying positive-parity excited states of a heavy quark {ital Q}{sub {ital j}} in terms of two universal functions of momentum transfer. These predictions are of interest in the study of {ital {bar B}}{r arrow}{ital D}{sub 2}{sup *}(2460), {ital D}{sub 1}(2420), {ital D}{sub 1}({similar to}2360), and {ital D}{sub 0}{sup *}({similar to}2360) semileptonic decays. We also discuss the connection between these results and the slope of the function {xi} (which determines the {ital {bar B}}{r arrow}{ital D} and {ital {bar B}}{r arrow}{ital D}{sup *} transition form factors) given by a heavy-quark sum rule suggested by Bjorken.