2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/187222We compute the Form Factors of the relevant scaling operators in a class of integrable models without internal symmetries by exploiting their cluster properties. Their identification is established by computing the corresponding anomalous dimensions by means of Delfino--Simonetti--Cardy sum--rule and further confirmed by comparing some universal ratios of the nearby non--integrable quantum field theories with their independent numerical determination.Latex file, 35 pages with 5 Postscript figuresHigh Energy Physics - Theorytext