Dispersive analysis of B → K (*) and B s → ϕ form factors

Gubernari, Nico; Reboud, Méril; van Dyk, Danny; Virto, Javier

Abstract

We propose a stronger formulation of the dispersive (or unitarity) bounds à la Boyd-Grinstein-Lebed (BGL), which are commonly applied in analyses of the hadronic form factors for B decays. In our approach, the existing bounds are split into several new bounds, thereby disentangling form factors that are jointly bounded in the common approach. This leads to stronger constraints for these objects, to a significant simplification of our numerical analysis, and to the removal of spurious correlations among the form factors. We apply these novel bounds to B¯→K¯∗ and B¯s→ϕ form factors by fitting them to purely theoretical constraints. Using a suitable parametrization, we take into account the form factors’ below-threshold branch cuts arising from on-shell B¯sπ0 and B¯sπ0π0 states, which so-far have been ignored in the literature. In this way, we eliminate a source of hard-to-quantify systematic uncertainties. We provide machine readable files to obtain the full set of the B¯→K¯∗ and B¯s→ϕ form factors in and beyond the entire semileptonic phase space.

Citation

Gubernari, N., Reboud, M., van Dyk, D., & Virto, J. (2023). Dispersive analysis of B → K (*) and B s → ϕ form factors. Journal of High Energy Physics, 2023(12), Article 153. https://doi.org/10.1007/jhep12%282023%29153

• Journal Article Type: Article
• Acceptance Date: Dec 7, 2023
• Online Publication Date: Dec 21, 2023
• Publication Date: 2023-12
• Deposit Date: Feb 22, 2024
• Publicly Available Date: Feb 22, 2024
• Journal: Journal of High Energy Physics
• Print ISSN: 1126-6708
• Electronic ISSN: 1029-8479
• Publisher: Scuola Internazionale Superiore di Studi Avanzati (SISSA)
• Peer Reviewed: Peer Reviewed
• Volume: 2023
• Issue: 12
• Article Number: 153
• DOI: https://doi.org/10.1007/jhep12%282023%29153
• Keywords: Bottom Quarks, Rare Decays, Lattice QCD, Semi-Leptonic Decays
• Public URL: https://durham-repository.worktribe.com/output/2082646