Unitarity bounds and form-factor predictions for $B$-meson decays
Fuente:
arXiv
Saved in:
| Main Author: | |
|---|---|
| Format: | Preprint |
| Published: |
2026
|
| Subjects: | |
| Online Access: | |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866918522914865152 |
|---|---|
| author | Gubernari, Nico |
| author_facet | Gubernari, Nico |
| contents | This paper is organized around three main objectives. First, I review in a pedagogical way the unitarity bounds for form factors in $B$-meson decays, together with the parametrizations 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 $B\toπ$ FFs. To treat the generic case, I fully develop the GG parametrization introduced in previous work and show how the same logic extends to a DM-like construction. Third, I perform three combined analyses and obtain form-factor predictions over the full semileptonic region: one for $B\toπ$ and $B_s\to K^{(*)}$, one for $B\to K^{(*)}$ and $B_s\to ϕ$, and one for $B\to D^{(*)}$ and $B_s\to D_s^{(*)}$. All numerical results, posterior samples, analysis files, and plots are provided in the supplementary material (https://github.com/gubernari/suppl-unitb). |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2605_26213 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Unitarity bounds and form-factor predictions for $B$-meson decays Gubernari, Nico High Energy Physics - Phenomenology This paper is organized around three main objectives. First, I review in a pedagogical way the unitarity bounds for form factors in $B$-meson decays, together with the parametrizations 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 $B\toπ$ FFs. To treat the generic case, I fully develop the GG parametrization introduced in previous work and show how the same logic extends to a DM-like construction. Third, I perform three combined analyses and obtain form-factor predictions over the full semileptonic region: one for $B\toπ$ and $B_s\to K^{(*)}$, one for $B\to K^{(*)}$ and $B_s\to ϕ$, and one for $B\to D^{(*)}$ and $B_s\to D_s^{(*)}$. All numerical results, posterior samples, analysis files, and plots are provided in the supplementary material (https://github.com/gubernari/suppl-unitb). |
| title | Unitarity bounds and form-factor predictions for $B$-meson decays |
| topic | High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2605.26213 |