2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/139840The evolution of the strong coupling constant $α_s$ from $M_Z$ to the GUT scale is presented, involving three-loop running and two-loop decoupling. Accordingly, the two-loop transition from the $\bar{\rm MS}$ to the $\bar{\rm DR}$ scheme is properly taken into account. We find that the three-loop effects are comparable to the experimental uncertainty for $α_s$.Submitted for the SUSY07 proceedings, 4 pages, 2 figuresHigh Energy Physics - Phenomenologytext