Semileptonic $B_{(s)}\to a_1(K_1)\ell^+ \ell^-$ decays via the light-cone sum rules with $B$-meson distribution amplitudes

Abstract: The form factors of semileptonic $B_{(s)}\to a_{1}(K_1)\, \ell^{+}\ell^{-}$, $ \ell=\tau,\mu,e$ transitions are investigated in the framework of the light-cone sum rules with $B$-meson distribution amplitudes, which play an important role in exclusive $B$ decays. The $B$-meson distribution amplitudes, $\varphi_{\pm}(\omega)$ are a model-dependent form, so we consider four different parameterizations which can provide a reasonable description of $\varphi_{\pm}(\omega)$ from QCD corrections. The branching fractions of these transitions are calculated. For a better analysis, a comparison of our results with the prediction of other models is provided.