2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/43964Some methods for the numerical computation of two-loop non-infrared vertices are reviewed. A new method is also proposed and compared to the old ones. Finally, some preliminary results are presented, concerning the evaluation of the fermionic corrections to $\sin^2θ_{\rm eff}^{\rm lept}$ through the described techniques.Talk presented at the final meeting of the European Network ``Physics at Colliders'', Montpellier, September 26-27, 2004. 14 pages, 4 figuresHigh Energy Physics - Phenomenologytext