paper

from the semileptonic decay and the properties of the meson distribution amplitude

arXiv:1309.5723 · doi:10.1016/j.nuclphysb.2014.04.021

Abstract

The improved QCD light-cone sum rule (LCSR) provides an effective way to deal with the heavy-to-light transition form factors (TFFs). Firstly, we adopt the improved LCSR approach to deal with the TFF up to twist-4 accuracy. Due to the elimination of the most uncertain twist-3 contribution and the large suppression of the twist-4 contribution, the obtained LCSR shall provide us a good platform for testing the -meson leading-twist DA. For the purpose, we suggest a new model for the -meson leading-twist DA (), whose longitudinal behavior is dominantly determined by a parameter . Moreover, we find its second Gegenbauer moment . Varying within certain region, one can conveniently mimic the -meson DA behavior suggested in the literature. Inversely, by comparing the estimations with the experimental data on the -meson involved processes, one can get a possible range for the parameter and a determined behavior for the -meson DA. Secondly, we discuss the TFF at the maximum recoil region and present a detailed comparison of it with the pQCD estimation and the experimental measurements. Thirdly, by applying the LCSR on , we study the CKM matrix element $\Vcb$ together with its uncertainties by adopting two types of processes, i.e. the -type and the -type. It is noted that a smaller shows a better agreement with the experimental value on $\Vcb$. For example, for the case of , we obtain and , whose first (second) uncertainty comes from the squared average of the mentioned theoretical (experimental) uncertainties.

13 pages, 10 figures. Reference updated and discussion improved. To be published in Nucl.Phys.B

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