Evaluation of Critical Dimension Composite Operators for the Stochastic Model A

We present the renormalization analysis of composite operators for the stochastic model A. Our main goal is to analyze analytically the damping behavior of the viscosity coefficient. To this end, we employ a field-theoretic perturbative renormalization group, which is performed by means of the \(\varepsilon = 4 - d\) -expansion. The critical exponent of viscosity is determined through the critical dimensions of composite operators of massless two-component model A. In particular, the procedure of calculation composite operators with the canonical dimension 8 is presented in detail. The renormalization analysis is carried out to the leading order of the perturbation theory.