Shear viscosity of a multi-component hadronic system

The shear viscosity eta and entropy density 8 of a hadron gas with zero baryon number density are calculated using the Chapman-Enskog and virial expansion approaches, respectively. Interactions are included via the K-matrix parametrization of cross sections preserving the unitarity of the S-matrix. In the four component mixture (pi - K - N - eta), a total of 57 resonances up to 2 GeV mass are included. Interactions forming resonances reduce the magnitude of eta and increase 8, both effects serving to progressively reduce eta/s as the temperature nears the QCD phase transition temperature.