Semileptonic D_(s) → Aℓ⁺ν and nonleptonic D → K₁(1270, 1400)π decays in LCSR

In this work, the transition form factors are calculated for the semileptonic D _(s) → Aℓ ⁺ ν where A = a ₁, b ₁, K ₁(1270, 1400), i.e. $D^{+}\to a_1^0(b_1^0,K_1^0){\ell }^{+}\nu$, $D^0\to a_1^{-}\left(b_1^{-}\right){\ell }^{+}\nu$, and $D_s^{+}\to K_1^0{\ell }^{+}\nu$ in the frame work of the light-cone QCD sum rules (LCSR) approach up to the twist-3 distribution amplitudes (DAs). Since the masses of these axial vector mesons are comparable to the charm quark mass, we keep out in our calculations all terms including m _A/m _c (all orders) in expansion of two-parton DAs. Branching ratio values are estimated for the semileptonic D _(s) → Aℓν and nonleptonic D→K ₁ (1270, 1400) π decays. A comparison is also made between our results and predictions of other methods and the existing experimental values. (paper)