Semileptonic B Decays into Excited Charmed Mesons (D1, D ∗ 2) in HQEFT

Exclusive semileptonic B decays into excited charmed mesons (D 1 , D * 2) are studied up to the order of 1/m Q in the framework of the heavy quark effective field theory (HQEFT), which contains the contributions of both particles and antiparticles. Two wave functions η b 0 and η c 0 , which characterize the contributions from the kinematic operator at the order of 1/m Q , are calculated by using QCD sum rule approach in HQEFT. Zero recoil values of other two wave functions κ ′ 1 and κ ′ 2 are extracted from the excited charmed-meson masses. Possible effects from the spin-dependent transition wave functions which arise from the magnetic operators at the order of 1/m Q are analyzed. It is shown that the experimental measurements for the branching ratios of B → D 1 lν and B → D * 2 lν can be understood in the framework of HQEFT.