Mass Uncertainties of f0(600) and f0(1370) and their Effects on   Determination of the Quark and Glueball Admixtures of the I=0 Scalar Mesons
  Within a nonlinear chiral Lagrangian framework the correlations between the quark and glueball admixtures of the isosinglet scalar mesons below 2 GeV and the current large uncertainties on the mass of the f0(600) and the f0(1370) are studied. The framework is formulated in terms of two scalar meson nonets (a two-quark nonet and a four-quark nonet) together with a scalar glueball. It is shown that while some properties of these states are sensitive to the mass of f0(600) and f0(1370), several relatively robust conclusions can be made: The f0(600), the f0(980), and the f0(1370) are admixtures of two and four quark components, with f0(600) being dominantly a non-strange four-quark state, and f0(980) and f0(1370) having a dominant two-quark component. Similarly, the f0(1500) and the f0(1710) have considerable two and four quark admixtures, but in addition have a large glueball component. For each state, a detailed analysis providing the numerical estimates of all components is given. It is also shown that this framework clearly favors the experimental values: m[f0(600)] < 700 MeV and m[f0(1370)] = 1300-1450 MeV. Moreover, an overall fit to the available data shows a reciprocal substructure for the f0(600) and the f0(1370), and a linear correlation between their masses of the form m [f0(1370)] = 0.29 m[f0(600)] + 1.22 GeV. The scalar glueball mass of 1.5-1.7 GeV is found in this analysis. 
Amir H. Fariborz