Simultaneous softening of σ and ϱ mesons associated with chiral restoration Original Research Article

Unitarized π-π scattering amplitudes in nuclear matter are studied with special emphasis on its complex poles in the scalar (σ) and vector (ϱ) channels. Partial restoration of chiral symmetry is modeled by the decrease of an in-medium pion decay constant View the MathML source. For large chiral restoration (View the MathML source), σ and ϱ poles show a large and simultaneous softening dictated by the Lambert W function. On the other hands, for small chiral restoration (View the MathML source, broadening (softening) is a dominant effect for ϱ (σ). In medium π-π cross sections associated with these spectral shifts are also studied.