2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/147928We present a self-consistent calculation of the finite temperature effective potential for $λΦ^4$ theory in four dimensions using a composite operator effective action. We find that in a spontaneously broken theory not only the so-called daisy and superdaisy graphs contribute to the next-to-leading order thermal mass, but also resummed non-local diagrams are of the same order, thus altering the effective potential at small effective mass.5 pages, Talk held at the 'Workshop on Quantum Infrared Physics', 6-8 June at ParisHigh Energy Physics - Phenomenologytext