2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/54488$λφ^4$ theory at finite temperature suffers from infrared divergences near the temperature at which the symmetry is restored. These divergences are handled using renormalization group methods. Flow equations which use a fiducial mass as flow parameter are well adapted to predicting the non-trivial critical exponents whose presence is reflected in these divergences. Using a fiducial temperature as flow parameter, we predict the critical temperature, at which the mass vanishes, in terms of the zero-temperature mass and coupling. We find some universal amplitude ratios which connect the broken and symmetric phases of the theory which agree well with those of the three-dimensional Ising model obtained from high- and low-temperature series expansions.7 pages of LaTeXHigh Energy Physics - TheoryCondensed Mattertext