2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/207293Measurements of on-shell ZZ production are described, using data from the DELPHI experiment at LEP in e+e- collisions at centre-of-mass energies between 183 and 209 GeV, corresponding to an integrated luminosity of about 665 pb^{-1}. Results obtained in each of the final states q anti-q q anti-q, nu anti-nu q anti-q, mu+ mu- q anti-q, e+ e- q anti-q, tau+ tau- q anti-q, l+ l- l+ l-, and nu anti-nu l+ l- (with l=e,mu) are presented. The measured production cross-sections are consistent with the Standard Model expectations. These results update and supersede those already published at 183 and 189 GeV.35 pages, 12 figures, Accepted by Eur. Phys. J. CHigh Energy Physics - Experimenttext