The scalar-isovector sector in the extended Linear Sigma Model
  We study basic properties of scalar hadronic resonances within the so-called extended Linear Sigma Model (eLSM), which is an effective model of QCD based on chiral symmetry and dilatation invariance. In particular, we focus on the mass and decay width of the scalar isovector state $a_{0}(1450)$ and perform a numerical study of the propagator pole(s) on the unphysical Riemann sheets. In this work, this meson is understood as a seed state explicitly included in the eLSM. Our results show that the inclusion of hadronic loops does not modify much the previously obtained tree-level results. Moreover the $a_{0}(980)$ cannot be found as a propagator pole generated by hadronic loop contributions. 
Thomas Wolkanowski and Francesco Giacosa
hep-ph