D Meson Leading-Twist Distribution Amplitude from B→Dlν̄l Semi-Leptonic Decay.

The D-meson leading-twist distribution amplitude (DA) is an universal physical quantity for applying QCD light-cone sum rules or perturbative QCD method to exclusive processes involving D-meson. Although several models have been used in the literature, we do not have enough knowledge to determine it. Inversely, one expects that the D-meson DA can be constrained in principle by the processes containing D-meson. In this paper, we try to extract the information of D-meson DA's behavior from the experimental data of B → D semi-leptonic decay. A revised light-cone harmonic oscillator model has been suggested. It can mimic most of the suggested D-meson DA behaviors, whose parameters can be fixed by the constraints from the processes involving D-meson. By combining the D-meson decay channel D → μ ν ̄ , the semi-leptonic decay B → D l ν ̄ l and the constrain that the probability of finding the leading Fock-state | c ̄ q > in the D-meson Fock state expansion, we restrict the parameter BD in our DA model as BD ∈ [0.00, 0.23]. In order to improve the complexity of the evolution of the oscillator model, we give the fitting formulas for the evolution of the model parameters. Then we calculate the branching ratios B ( B ¯ 0 → D + l ν l) and B (B − → D 0 l ν ̄ l) , which agree with the experimental data. [ABSTRACT FROM AUTHOR]