Regular Article - Theoretical Physics
Theory determination of form factors at
Universität Siegen, Walter-Flex Straße 3, 57072, Siegen, Germany
2 Excellence Cluster Universe, Technische Universität München, Boltzmannstr. 2, 85748, Garching, Germany
3 Dipartimento di Fisica, Università di Torino & INFN, Sezione di Torino, 10125, Turin, Italy
4 Technische Universität München, James-Franck-Straße 1, 85748, Garching, Germany
Accepted: 6 January 2020
Published online: 31 January 2020
We carry out an analysis of the full set of ten form factors within the framework of the Heavy-Quark Expansion (HQE) to order , 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 light-cone sum rules, in combination with constraints from lattice QCD, QCD three-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 measurements. The coefficients entering at the level are found to be of , indicating convergence of the HQE. The phenomenological implications of our study include an updated exclusive determination of 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 , the polarization observables , and the longitudinal polarization fraction . Posterior samples for the HQE parameters are provided as ancillary files, allowing for their use in subsequent studies.
© The Author(s) 2020
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