Branching fractions and polarizations of $D\to V(\ddot{I}‰,\ddot{I},K^{\ast })\ell \hat{I}{½}_{\ell }$ within QCD LCSR

Abstract

In this paper, we make a detailed study about the $D\to V$ helicity form factors (HFFs) within the framework of QCD light-cone sum rule (LCSR) up to twist-4 accuracy. After extrapolating the LCSR predictions of HFFs to the whole physical $q^2$-region, we get the longitudinal, transverse and total $|V_{cq}|$-independent decay widths of semileptonic decay $D\to V{\ell }^{+}\hat{I}{½}_{\ell }$. Meanwhile, the branching fractions of these decays are also obtained by using the $D^0(D^{+})$-meson lifetime, which agree well with the BES-III results within errors. As a further step, we also investigate the differential and mean predictions for charged lepton (vector meson) polarization in the final state $P_{\mathrm{L},\mathrm{T}}^{\ell }$ ($F_{\mathrm{L},\mathrm{T}}^{\ell }$), the forward-backward asymmetry ${\mathcal{A}}_{\mathrm{FB}}^{\ell }$, and the lepton-side convexity parameters ${\mathcal{C}}_{\mathrm{F}}^{\ell }$. Our predictions are consistent with Covariant Confining Quark Model results within the errors. Thus, we think the LCSR approach for HFFs is applicable for dealing with the $D$-meson semileptonic decays.

15 pages, 5 figures, 7 tables; minor changes; revised version to appear in Physical Review Research