2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/181865In this paper we calculate the weak form factors of the decays $B_c(B)\to Dl\tildeν$ by using the chiral current correlator within the framework of the QCD light-cone sum rules (LCSR). The expressions of the form factors only depend on the leading twist distribution amplitude (DA) of the $D$ meson. Three models of the $D$-meson distribution amplitude are employed and the calculated form factor $F_{B_c\to D}(0)$ is given. Our prediction, by using the $D$-meson distribution amplitude with the exponential suppression at the end points, is compatible with other approaches, and favors the three-points sum rules (3PSR) approach with the Coulumb corrections included.12 pages, 3 figuresHigh Energy Physics - Phenomenologytext