2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/39358The significance of thermal dilepton radiation at intermediate invariant masses (1GeV<M<3GeV) in ultrarelativistic heavy-ion collisions is investigated. At CERN-SpS energies, a consistent explanation of the excess observed by NA50 can be given. At RHIC energies the thermal signal is dominated by early emission indicative for QGP formation. Chemical under-saturation effects and the competition with open-charm contributions are addressed.Invited talk at the International Workshop XXVIII on Gross Properties of Nuclei and Nuclear Excitations, 'Hadrons in Dense Matter', Hirschegg (Austria), Jan. 16-22, 2000; 8 pages LaTeX including 11 eps/ps-figuresHigh Energy Physics - PhenomenologyNuclear Theorytext