Mass and width of the σ meson at finite density Original Research Article

The ππ interaction in the σ channel is studied at finite densities in a chiral unitary approach. We present some results on the σ meson pole position. We also analyze the (γ, ππ) reaction on nucleons and nuclei in the kinematical region where the scalar isoscalar ππ scattering amplitude is influenced by the low mass of the σ in nuclei, and has a large enhancement close to the position of the σ pole.