Exclusive semileptonic $B$-meson decays using lattice QCD and unitarity

TL;DR

This paper applies a non-perturbative, model-independent dispersion matrix approach to determine hadronic form factors in exclusive semileptonic B-meson decays, enabling precise extraction of CKM matrix elements and testing lepton flavor universality.

Contribution

It introduces a novel dispersion matrix method for form factor determination that avoids parameterization, improving the accuracy of CKM element extraction from lattice QCD results.

Findings

Determined form factors across the entire kinematic range without parameterization.

Provided new estimates for CKM matrix elements |V_cb| and |V_ub|.

Calculated lepton flavor universality ratios for B decays.

Abstract

We present the results of the application of the Dispersion Matrix approach to exclusive semileptonic $B$-meson decays. This method allows to determine the hadronic form factors in a non-perturbative and completely model-independent way. Starting from lattice results available at large values of the momentum transfer, the behaviour of the form factors in their whole kinematical range is obtained without introducing any parameterization of their momentum dependence. We will focus on the determination of the Cabibbo-Kobayashi-Maskawa matrix elements $\vert V_{cb} \vert$ and $\vert V_{ub} \vert$ through the analysis of $B_{(s)} \to D_{(s)}^{(*)} \ell \nu$ and $B_{(s)} \to \pi(K) \ell \nu$ decays. New theoretical determinations of the Lepton Flavour Universality ratios relevant for these transitions will be also presented.