2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/223621We study the thermodynamics of massless phi-fourth theory using screened perturbation theory, which is a way to systematically reorganise the perturbative series. The free energy and pressure are calculated through four loops in a double expansion in powers of g^2 and m/T, where m is a thermal mass of order gT. The result is truncated at order g^7. We find that the convergence properties are significantly improved compared to the weak-coupling expansion.Talk given at Strong and Electroweak Matter 2008, Amsterdam, Aug. 25-29 2008. 4 pages, 1 figureHigh Energy Physics - Phenomenologytext