Field theory near the critical temperature

Abstract

Field theory at nonvanishing temperature beyond perturbation theory is discussed for the $N$-component $O(N)$-symmetric scalar theory. We compute the effective potential directly in three dimensions using an exact evolution equation for an effective action with an infrared cutoff. A suitable truncation is solved numerically. We obtain a detailed quantitative picture of the scaling form of the equation of state in the vicinity of the critical temperature of a second order phase transition.

11 pages, 3 figures. Talk given at the International School of Subnuclear Physics, 34th Course: Effective Theories and Fundamental Interactions, Erice-Sicily, 3-12 July 1996