Determination of B-meson distribution amplitudes from B → π, K, D transition form factors

A bstract Recent work on B → π , K and B → D form factors from lattice QCD and light-cone sum rules has made it possible to constrain the inverse moment λ B of the B -meson light-cone distribution amplitudes by performing a global fit of B → π , K , D form factors. We have compiled the B → π , K , D form factors calculated by the HPQCD, MILC, and RBC/UKQCD collaborations in the large q 2 region. By employing an three-parameter ansatz of the B -meson light-cone distribution amplitudes, we express the B → π , K , D form factors at q 2 = 0 that are calculated from light-cone sum rules, in terms of the inverse moment λ B of the leading-twist B -meson light-cone distribution amplitude. In the B → πℓν channel, we also include the available q 2 -binned experimental data from the BaBar, Belle, and Belle II collaborations. Using the Bourrely-Caprini-Lellouch parametrization, we perform a global fit and obtain λ B = 217(19)₋₁₇⁺⁸² 217 19 − 17 + 82 MeV and | V ub | = 3.68(13)₋₁⁺⁰ 3.68 13 − 1 + 0 × 10 −3 . The second uncertainty is obtained by constraining λ B > 200 MeV and varying the inverse logarithmic moments σ̂₁ σ ̂ 1 ∈ [−0.7, 0.7] and σ̂₂ σ ̂ 2 ∈ [−6, 6], which represents the model-dependent uncertainty from the B -meson light-cone distribution amplitudes. When taking into account λ B and σ̂₁ σ ̂ 1 as fitting parameters simultaneously, the intervals of our preditions are λ B = [208, 324] MeV and σ̂₁ σ ̂ 1 = [−0.7, 0.27].