Heavy + heavy and heavy + light pseudoscalar to vector semileptonic transitions

Abstract

Using a symmetry-preserving regularisation of a vector $$\times $$ × vector contact interaction (SCI), we complete a systematic treatment of twelve semileptonic transitions with vector meson final states: $$D\rightarrow \rho $$ D → ρ , $$D_{(s)}\rightarrow K^*$$ D ( s ) → K ∗ , $$D_s\rightarrow \phi $$ D s → ϕ , $$B\rightarrow \rho $$ B → ρ , $$B_s\rightarrow K^*$$ B s → K ∗ , $$B_{(s)}\rightarrow D_{(s)}^*$$ B ( s ) → D ( s ) ∗ , $$B_c \rightarrow B_{(s)}^*, J/\psi , D^*$$ B c → B ( s ) ∗ , J / ψ , D ∗ ; and thereby finalise a unified analysis of semileptonic decays of heavy + heavy and heavy + light pseudoscalar mesons to both pseudoscalar and vector meson final states. The analysis is marked by algebraic simplicity, few parameters, and the ability to consistently describe systems from Nambu-Goldstone modes to heavy + heavy mesons. Regarding the behaviour of the transition form factors, the SCI results compare well wherever sound experimental or independent theory analyses are available; hence, the SCI branching fraction predictions should be a reasonable guide. Considering the ratios $$R(D_{(s)}^{(*)})$$ R ( D ( s ) ( ∗ ) ) , $$R(J/\psi )$$ R ( J / ψ ) , $$R(\eta _c)$$ R ( η c ) , whose values are key tests of lepton universality in weak interactions, the SCI values agree with Standard Model predictions. The $$B_{(s)}\rightarrow D_{(s)}^*$$ B ( s ) → D ( s ) ∗ transitions are used to predict the precursor functions that evolve into the universal Isgur–Wise function in the heavy-quark limit, with results that conform with those from other sources where such are available. The study also exposes effects on the transition form factors that flow from interference between emergent hadron mass from the strong interaction and Higgs boson couplings via current-quark masses, including flavour symmetry violation.

U(5) Nambu-Jona-Lasinio model with flavor dependent coupling constants: pseudoscalar and scalar mesons masses

“…In Table (4) the resulting normalized flavor-dependent coupling constants calculated with Eqs. (16,15) are shown for the four SETs of parameters for all i, j channels. Before normalization, the corrections to the diagonal coupling constants ∆G ii are, at most, nearly of the order of 0.25 × G 0 in agreement with previous estimates for polarization effect for light quarks NJL [61,62].…”

“…Some ways of describing reasonably well heavy hadrons under certain ranges of energies were given by, for example, Heavy Quark Effective Field Theory (HQEFT) and models from Heavy quark symmetries including those for heavy-light mesons [4,7,2,9,10,11,12,13]. In spite of the continuous efforts to obtain results from first principles QCD, lattice QCD [14], and continuous approaches in the Euclidean space [15], it still is interesting to consider effective models in which the physical meaning of parameter are usually clear, also new effects can be proposed and tested and, for more reliable models, results can lead to the identification of the most important degrees of freedom with grounds in QCD. Notwithstanding, it becomes important to disantangle mathematical features of the model and issues that must be directly traced back to the QCD degrees of freedom [16,17].…”