2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/176653We present the results for the full electroweak two-loop bosonic contributions to the effective leptonic mixing angle of the $Z$ boson, $\sin^2θ_{\rm eff}$, in the Standard Model. A method applied to extract collinear divergences from two-loop vertex-functions is described. Comparisons of our results with those from a recent previous calculation show complete agreement.14 pages, 3 figures, 4 tablesHigh Energy Physics - Phenomenologytext