2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/83235We propose a soluble model to incorporate the nonlinear effects in the transition probabilities of the multiphonon Giant Dipole Resonances based on the SU(1,1) algebra. Analytical expressions for the multi-phonon transition probabilities are derived. For reasonably small magnitude of nonlinearity $x\simeq 0.1-0.2$ enhancement factor for the Double Giant Resonance excitation probabilities and the cross sections %in relativistic ion collisions reaches values $1.3-2$ compatible with experimental data.13 pages, 3 ps figures, Invited talk given at the International Workshop on "Collective Excitations in Fermi and Bose Systems", September 14--17, 1998, Serra Negra, Brazil, to be published by World Scietific, eds. Carlos Bertulani and Mahir HusseinNuclear Theorytext