In-medium Pion-Pion Interaction and Chiral Symmetry Restoration
  We discuss medium modifications of the unitarized pion-pion interaction in the nuclear medium. We incorporate both the effects of chiral symmetry restoration and the influence of collective nuclear pionic modes, originating from the p-wave coupling of the pion to delta-hole configurations. We show how the resulting strong enhancement of the sigma-meson spectral function is related to large fluctuations of the condensate associated with the partial restoration of chiral symmetry. 
D. Davesne (Institut de Physique Nucleaire, Lyon, France), Y.J. Zhang   (Joint Laboratory for Quantum Optics, Shanghai Insti...