The decay constants of heavy-light mesons in a two-tier Bethe-Salpeter model

Leptonic decay widths for pseudoscalar mesons are calculated in a QCD-motivated Bethe-Salpeter formalism on a two-tier basis. This model, which is characterised by a Lorentz-invariant confining kernel that depends on the relativistic reduced mass defined in accordance with the Wightman-Garding definition of the internal 4-momenta qμ, has already shown precision fits to the spectra of qq-bar, qQ-bar and qqq hadrons apart from exhibiting an eplicit Regge-asymptotic behaviour (M2∼N). The leptonic decay constants thus obtained with no free parameters, are (in MeV units), fP =134(π), 166(K); 158(D); 94.9(B), 114(BS). (author)