Year: 2026
Type: article
Abstract: A bstract This paper has three main aims. First, I review in a pedagogical way the unitarity bounds for form factors in B -meson decays, together with the parametrisations most commonly used in phenomenological analyses. These include BGL, BCL, CLN, and the Dispersive Matrix (DM) method. I also clarify the relation between BGL and DM, showing that they are two equivalent implementations of the same unitarity information. Second, I demonstrate that the standard BGL and DM constructions are strictly rigorous only when no subthreshold cuts are present. For B -meson decays, this requirement is fulfilled exclusively by the B → π FFs. To treat the generic case, I fully develop the GG parametrisation introduced in a previous paper and show how the same logic extends to a DM-like construction. Third, I perform three novel combined analyses of form factors and obtain predictions over the full semileptonic region. The first analysis concerns the form factors for B → π and B s → K (∗) , the second those for B → K (∗) and B s → ϕ , and the third those for B → D (∗) and $$ {B}_s\to {D}_s^{\left(\ast \right)} $$ B s → D s ∗ . All numerical results, posterior samples, analysis files, and plots are provided in the supplementary material [1].
Source: Journal of High Energy Physics
Author: Nico Gubernari
Institutions: University of Bonn, University of Cambridge
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W7162486554