The (4, 4*) ⊕ (4*, 4) model of broken chiral SU (4) × SU (4) symmetry has been used to calculate the third-order coupling constants involving charmed and ordinary pseudoscalar mesons. These coupling constants are exploited to derive some interesting new relations among the masses and decay constants of these charmed particles. Using the known masses and decay constants as inputs, we exploit these relations to predict:F_D = −1·41F_π,F_F = −1·13F_π,F_D/F_F = 1·25,m(D_s) = 1·43 GeV,m(F_s) = 1·39 GeV andm(K_s) = 1·02 GeV.

The heavy mesons of the charmonium and upsilon family are described in an alternative static potential model chosen in a combination of Hulthen and linear potential. We find that the quark-confining potential in the form of an equal admixture of vector and scalar parts successfully explains the fine-hyperfine structures of$$c\bar c$$ and$$b\bar b$$ systems in a flavour-independent manner. The leptonic decay widths of the vector mesons ofψ and γ families are calculated taking into account the Poggio-Schnitzer correction. We obtain some of the bound states of the yet-to-be observed$$t\bar t$$ system for thet-quark mass ranging from 50 to 200 GeV.