Decay widths of resonances and pion scattering lengths in a globally   invariant linear sigma model with vector mesons
  We calculate low-energy meson decay processes and pion-pion scattering lengths in a two-flavour linear sigma model with global chiral symmetry, exploring the scenario in which the scalar mesons $f_0$(600) and $a_0$(980) are assumed to be $\bar q q$ states. 
Denis Parganlija, Francesco Giacosa and Dirk H. Rischke