We 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.Comment: Talk given at Strong and Electroweak Matter 2008, Amsterdam, Aug.
25-29 2008. 4 pages, 1 figur
