Abstract
A symmetry-preserving regularisation of a vector times vector contact interaction (SCI) is used to deliver a unified treatment of semileptonic transitions involving pi , K, D_{(s)}, B_{(s,c)} initial states. The framework is characterised by algebraic simplicity, few parameters, and the ability to simultaneously treat systems from Nambu–Goldstone modes to heavy+heavy mesons. Although the SCI form factors are typically somewhat stiff, the results are comparable with experiment and rigorous theory results. Hence, predictions for the five unmeasured B_{s,c} branching fractions should be a reasonable guide. The analysis provides insights into the effects of Higgs boson couplings via current-quark masses on the transition form factors; and results on B_{(s)}rightarrow D_{(s)} transitions yield a prediction for the Isgur–Wise function in fair agreement with contemporary data.
Highlights
Pseudoscalar mesons are fascinating for many reasons
In the light-quark sector, the pion is remarkably light owing to dynamical chiral symmetry breaking [1]; itself, a corollary of emergent hadron mass (EHM) [2,3]
A e-mail: znxu@smail.nju.edu.cn b e-mail: phycui@nju.edu.cn c e-mail: cdroberts@nju.edu.cn d e-mail: cxu@nju.edu.cn. These observations are highlighted by studies of the leptonic and semileptonic decays of the π and K, which measure the scale of EHM, the strength of Higgs boson couplings into quantum chromodynamics (QCD), and the size of the entries in the Cabbibo–Kobayashi–Maskawa (CKM) matrix that generate the associated flavour-changing weak interactions
Summary
Pseudoscalar mesons are fascinating for many reasons. In the light-quark sector, the pion is remarkably light owing to dynamical chiral symmetry breaking [1]; itself, a corollary of emergent hadron mass (EHM) [2,3]. Comparisons between pion and kaon properties provide information on empirical expressions of EHM and insights into the constructive interference between Nature’s two most basic mass generating mechanisms [4,5,6,7,8,9] These observations are highlighted by studies of the leptonic and semileptonic decays of the π and K , which measure the scale of EHM, the strength of Higgs boson couplings into quantum chromodynamics (QCD), and the size of the entries in the Cabbibo–Kobayashi–Maskawa (CKM) matrix that generate the associated flavour-changing weak interactions. In these cases, the CKM matrix elements are |Vud | and |Vus|. One is provided by calculations made with a symmetry-preserving formulation of a vector × vec-
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