Minimal renormalization without ε expansion: Critical behavior above and belowTc

We present a field-theoretic renormalization-group treatment of the critical behavior of the ${\mathit{cphi}}^4$ model within the minimal-subtraction scheme at fixed dimension d<4. We show that correlation functions above and below ${\mathit{T}}_{\mathit{c}}$ can be calculated within this renormalization scheme without using the ε=4-d expansion. This is demonstrated for the specific heat, for the order parameter, and for the superfluid density (stiffness constant). Various asymptotic amplitudes and correction amplitudes are determined, and some of their universal ratios are calculated in three dimensions. Our result for ${\mathit{a}}_{\mathit{c}}^{\mathrm{-}}$/${\mathit{a}}_{\mathrm{\rho }\mathit{s}}$ eliminates a previous error of the ε expansion regarding the sign of this ratio for d=3 and n=2.