2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/197060Since present Monte Carlo algorithms for lattice QCD may become trapped in a fixed topological charge sector, it is important to understand the effect of calculating at fixed topology. In this work, we show that although the restriction to a fixed topological sector becomes irrelevant in the infinite volume limit, it gives rise to characteristic finite size effects due to contributions from all $θ$-vacua. We calculate these effects and show how to extract physical results from numerical data obtained at fixed topology.14 Pages, no fguresHigh Energy Physics - Latticetext