Perturbative corrections to B -> D form factors in QCD

Yu-Ming Wang, Yan-Bing Wei, Yue-Long Shen, Cai-Dian Lu

We compute perturbative QCD corrections to B -> D form factors at leading power in Lambda/m(b), at large hadronic recoil, from the light-cone sum rules (LCSR) with B-meson distribution amplitudes in HQET. QCD factorization for the vacuum-to-B-meson correlation function with an interpolating current for the D-meson is demonstrated explicitly at one loop with the power counting scheme m(c) similar to O (root Lambda m(b)). The jet functions encoding information of the hard-collinear dynamics in the above-mentioned correlation function are complicated by the appearance of an additional hard-collinear scale mc, compared to the counterparts entering the factorization formula of the vacuum-to-B-meson correction function for the construction of B -> pi from factors. Inspecting the next-to-leading-logarithmic sum rules for the form factors of B -> Dlv indicates that perturbative corrections to the hard-collinear functions are more profound than that for the hard functions, with the default theory inputs, in the physical kinematic region. We further compute the subleading power correction induced by the three-particle quark-gluon distribution amplitudes of the B-meson at tree level employing the background gluon field approach. The LCSR predictions for the semileptonic B -> Dlv form factors are then extrapolated to the entire kinematic region with the z-series parametrization. Phenomenological implications of our determinations for the form factors f(BD)(+,0) (q(2)) are explored by investigating the (differential) branching fractions and the R(D) ratio of B -> Dlv and by determining the CKM matrix element vertical bar V-cb vertical bar from the total decay rate of B -> D mu nu.

Particle Physics
External organisation(s)
Nankai University, University of the Chinese Academy of Sciences, Chinese Academy of Sciences (CAS), Ocean University of China
Journal of High Energy Physics
No. of pages
Publication date
Peer reviewed
Austrian Fields of Science 2012
103012 High energy physics
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