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Article
Report number arXiv:2303.11285 ; CERN-TH-2023-047
Title Bayesian inference for form-factor fits regulated by unitarity and analyticity
Author(s) Flynn, J.M. (Southampton U.) ; Jüttner, A. (Southampton U. ; CERN) ; Tsang, J.T. (CERN)
Publication 2023-12-27
Imprint 2023-03-20
Number of pages 46
Note 46 pages, 8 figures, version as published in JHEP with updated references, extended discussion of the truncation dependence (Sec. 3.4) and the asymptotic behaviour of the BGL expansion (App. C)
In: JHEP 2312 (2023) 175
DOI 10.1007/JHEP12(2023)175
Subject category hep-lat ; Particle Physics - Lattice ; hep-ph ; Particle Physics - Phenomenology
Abstract We propose a model-independent framework for fitting hadronic form-factor data, which is often only available at discrete kinematical points, using parameterisations based on to unitarity and analyticity. In this novel approach the latter two properties of quantum-field theory regulate the ill-posed fitting problem and allow model-independent predictions over the entire physical range. Kinematical constraints, for example for the vector and scalar form factors in semileptonic meson decays, can be imposed exactly. The core formulae are straight-forward to implement with standard math libraries. We take account of a generalisation of the original Boyd Grinstein Lebed (BGL) unitarity constraint for form factors and demonstrate our method for the exclusive semileptonic decay $B_s\to K \ell \nu$, for which we make a number of phenomenologically relevant predictions, including the CKM matrix element $|V_{ub}|$.
Copyright/License preprint: (License: arXiv nonexclusive-distrib 1.0)
publication: © 2023-2024 The Authors (License: CC-BY-4.0), sponsored by SCOAP³



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