Theory determination of (B)over-bar → D(*) l-(ν)over-bar form factors at O(1/mc2)

We carry out an analysis of the full set of ten B. D(*) form factors within the framework of the HeavyQuark Expansion (HQE) to orderO as, 1/mb, 1/m2c, both with and without the use of experimental data. This becomes possible due to a recent calculation of these form factors at and beyond the maximal physical recoil using QCD lightcone sum rules, in combination with constraints from lattice QCD, QCDthree-point sum rules and unitarity. We find good agreement amongst the various theoretical results, as well as between the theoretical results and the kinematical distributions in B. D(*){e-, mu-} . measurements. The coefficients entering at the 1/m2c level are found to be of O(1), indicating convergence of the HQE. The phenomenological implications of our study include an updated exclusive determination of |Vcb| in the HQE, which is compatible with both the exclusive determination using the BGL parametrization and with the inclusive determination. We also revisit predictions for the lepton-flavour universality ratios RD(*), the t polarization observables PD(*) t, and the longitudinal polarization fraction FL. Posterior samples for the HQE parameters are provided as ancillary files, allowing for their use in subsequent studies.