TEMPERATURE-DEPENDENCE AND FRAGMENTATION OF THE PARTICLE-HOLE GIANT-RESONANCES

We evaluate the spreading width of the giant multipole resonances at f inite temperature using the discontinuity in the second derivative of the Green's function of the vibrational boson, in the Matsubara's fram ework. Our method allows us to identify the processes that contribute to the spreading width in terms of the Feynman diagrammatic expansion of the full boson propagator. We have applied the calculation of the s preading width to the Pb-208 and the Zr-90 obtaining an increment of t he spreading width with the temperature. We have not reached any satur ation of the spreading width increment. at least up to the temperature of our calculation.