Decay constants, smoothness and spin-zero charm mesons in broken chiral SU(4) x SU(4) symmetry

Considering the general form of the symmetry breaking Hamiltonian including isospin violation term u3 in the framework of chiral SU(4) x SU(4) model, and imposing smoothness assumption on certain three-point vertex functions, we estimate the symmetry breaking and vacuum asymmetry parameters, masses and weak decay constants of spin-zero charm mesons in terms of known meson masses and one input variable F = f sub( k)/f sub(π). Our kinematical method predicts m sub( d( s)) = 3.3 GeV, m sub( f( s)) = 3.6 GeV and the non-electromagnetic mass splittings, (m sub(D+(P)) - m sub(D0(P)))sub(u3) asymptotically equals (m sub(D+(S)) - m sub(D0(S)))sub(u3) = 1.5 MeV for F = 1.28. The weak decay constant ratios are obtained to be f sub( d( p))/f sub( k) asymptotically equals f sub( f( p))/f sub( k) = 1.03, f sub( d( s))/f sub( k) asymptotically equals f sub( f( s))/f sub( k) = 0.30, which are in general much lower than the values predicted by the linear σ-model calculations. The mixing angle between eta'(958) and eta''(2750) is also obtained to be -- 400, in agreement with the recent predictions. (author)