On nature of the scalar-isoscalar mesons in the uniformizing-variable   method based on analyticity and unitarity
  The experimental data on the processes $\pi\pi\to\pi\pi,K\bar{K},\eta\eta,\eta\eta^\prime$ in the $I^GJ^{PC}=0^+0^{++}$ channel have been jointly analyzed to study the status and nature of the $f_0$. The method of analysis is based on analyticity and unitarity and uses an uniformization procedure. Some spectroscopic implications from results of the analysis are discussed. 
Yurii S. Surovtsev, Petr Bydzovsky, and Valery E. Lyubovitskij
hep-ph