Anomalous thresholds in $B\to (P,V)γ^*$ form factors
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| Format: | Preprint |
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2024
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| _version_ | 1866909274790166528 |
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| author | Mutke, Simon Hoferichter, Martin Kubis, Bastian |
| author_facet | Mutke, Simon Hoferichter, Martin Kubis, Bastian |
| contents | We study the effects of anomalous thresholds on the non-local form factors describing the hadronization of the light-quark contribution to $B\to(P,V)γ^*$ transitions. Starting from a comprehensive discussion of anomalous thresholds in the triangle loop function for different mass configurations, we detail how the dispersion relation for $ππ$ intermediate states is affected by contour deformations mandated by the anomalous branch points. Phenomenological estimates of the size of the anomalous contributions to the form factors are provided with couplings determined from measured branching fractions and Dalitz plot distributions. Our key finding is that anomalous effects are suppressed on the $ρ(770)$ resonance, while off-peak the effects can become as large as $\mathcal{O}(10\%)$ of the full (light-quark-loop induced) non-local form factors. We comment on future generalizations towards higher intermediate states and the charm loop, outlining how the dispersive framework established in this work could help improve the non-local form factors needed as input for a robust interpretation of $B\to (P,V)\ell^+\ell^-$ decays. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2406_14608 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Anomalous thresholds in $B\to (P,V)γ^*$ form factors Mutke, Simon Hoferichter, Martin Kubis, Bastian High Energy Physics - Phenomenology High Energy Physics - Experiment Nuclear Theory We study the effects of anomalous thresholds on the non-local form factors describing the hadronization of the light-quark contribution to $B\to(P,V)γ^*$ transitions. Starting from a comprehensive discussion of anomalous thresholds in the triangle loop function for different mass configurations, we detail how the dispersion relation for $ππ$ intermediate states is affected by contour deformations mandated by the anomalous branch points. Phenomenological estimates of the size of the anomalous contributions to the form factors are provided with couplings determined from measured branching fractions and Dalitz plot distributions. Our key finding is that anomalous effects are suppressed on the $ρ(770)$ resonance, while off-peak the effects can become as large as $\mathcal{O}(10\%)$ of the full (light-quark-loop induced) non-local form factors. We comment on future generalizations towards higher intermediate states and the charm loop, outlining how the dispersive framework established in this work could help improve the non-local form factors needed as input for a robust interpretation of $B\to (P,V)\ell^+\ell^-$ decays. |
| title | Anomalous thresholds in $B\to (P,V)γ^*$ form factors |
| topic | High Energy Physics - Phenomenology High Energy Physics - Experiment Nuclear Theory |
| url | https://arxiv.org/abs/2406.14608 |