The Imaginary Part of the Nucleon Self-energy in Hot Nuclear Matter

A semiphenomenological approach to the nucleon self-energy in nuclear matter at nite temperatures is followed. It combines elements of Thermo Field Dynamics for the treatment of nite temperature with a model for the self-energy, which evaluates the second order diagrams taking the needed dynamics of the NN interaction from experiment. The approach proved to be accurate at zero temperature to reproduce Im and other properties of nucleons in matter. In the present case we apply it to determine Im at nite temperatures. An e ective NN cross section is deduced which can be easily used in analyses of heavy ion reactions.