Two-photon decays of rho and omega mesons and strong decays rho -> eta   pi and omega -> pi pi in dense matter
  Two-photon decays of rho and omega mesons and strong decays rho -> eta pi and omega -> pi pi are described in the quark Nambu-Jona-Lasinio(NJL) model in dense medium. Decays of rho-meson are especially interesting because they contain intermediate a_0-meson which became a sharp resonance in the vicinity of phase transition of hadron matter into quark-gluon plasma. This leads to increasing rho decay width and, as a result, two-photon decay of rho-meson in medium became comparable with two-photon decays of scalar and pseudoscalar mesons in vacuum. Similar effect take place in the strong decay rho -> eta pi. 
A.E.Radzhabov and M.K.Volkov