Abstract
Effective field theories provide a suitable framework for both particle physics and statistical physics. We delve deeper into the study of the effective three-dimensional scalar field theory for its application to statistical physics, especially considering the role of the sextic coupling in the tricritical-to-critical crossover. The three-loop renormalization of the mass and the two coupling constants that we perform allows us to obtain, for the first time, the complete renormalization group flow of the couplings in that order. We analyze what universality means in this problem and how we can recover non-universal terms from the renormalization group beta functions. The crossover is realized by the convergence of the renormalization group flow towards the line connecting the tricritical and critical fixed points.