2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/185260We establish constraints on a general four-fermion contact interaction from precise measurements of electroweak parameters. We compute the one-loop contribution for the leptonic $Z$ width, anomalous magnetic, weak-magnetic, electric and weak dipole moments of leptons in order to extract bounds on the energy scale of these effective interactions.16 pages, RevTeX, two figuresHigh Energy Physics - Phenomenologytext