Footprint in fitting B→ D vector form factor and determination for D-meson leading-twist LCDA

In this paper, we fit the B→ D B → D vector transition form factor (TFF) by using the data measured by BABAR and Belle Collaborations within Monte Carlo (MC) method. Meanwhile, the B→ D B → D TFF is also calculated by using the QCD light-cone sum rules approach (LCSRs) within right-handed chiral current correlation function. In the TFF, D -meson leading-twist light-cone distribution amplitude (LCDA) is the most important non-perturbative input parameter, the precise behavior of which is mainly determined by the parameter B2;D B 2 ; D in the light-cone harmonic oscillator model. Through fitting the TFF, we determine the value B2;D=0.445 B 2 ; D = 0.445 . Then, we present the curve of D -meson leading-twist LCDA in comparison with other theoretical approaches. Subsequently, the B→ D B → D TFF f₊BD(q²) f + BD ( q 2 ) at the large recoil region is f₊BD(0)=0.648-0.063+0.067 f + BD ( 0 ) = 0 . 648 - 0.063 + 0.067 , which is compared in detail with theoretical estimates and experimental measurements. Furthermore, we calculated the decay width and branching fractions of the Cabibbo-favored semileptonic decays B→ D ⁺ν B → D ℓ + ν ℓ , which lead to the results B(B⁰→ D⁻ ⁺ν ) =(2.10-0.38+0.44)× 10⁻² B ( B 0 → D - ℓ + ν ℓ )