Renormalization of the f(0)(980) and a(0)(980) scalar resonances in a nuclear medium

The meson-meson interaction in the scalar sector in the presence of a nucle ar medium is studied with particular attention to the change of the propert ies of the f(0)(980) and a(0)(980) resonances. By using a chiral unitary ap proach which generates the f(0) and a(0) resonances and reproduces their fr ee properties, we find that the position of the resonances in the medium is barely changed but their widths are considerably broadened. New many body corrections generating from higher orders in the chiral Lagrangian plus the contribution from N*h excitations, not considered before in connection wit h the pi pi interaction in the nuclear medium, are also investigated. (C) 2 000 Elsevier Science B.V. All rights reserved.