2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/207238The exclusive production of proton-antiproton pairs in the collisions of two quasi-real photons had been studied using data taken at sqrt(s)_ee=183 GeV and 189 GeV with the OPAL detector at LEP. Results are presented for Ppbar invariant masses, W, in the range 2.15 W< <3.95 GeV. The cross-section measurements are compared with previous data and with recent analytic calculations based on the quark-diquark model.21 pages, 5 figuresHigh Energy Physics - Experimenttext