2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/171894We consider a self-interacting scalar field in a de Sitter background and deal with the associated infrared divergences in a purely diagrammatic way using the in-in formalism. In the particular case of a large N O(N) invariant scalar field theory with quartic self-interactions we recover the result that the connected four-point correlation function, which is a signal of non-Gaussianity, is non-perturbatively enhanced with respect to its tree-level value.10 pages, 7 figures, acknoledgments addedGeneral Relativity and Quantum Cosmologytext