Numerical calculation of scaling exponents of percolation process in the framework of renormalization group approach

We use the renormalization group theory to study the directed bond percolation (Gribov process) near its second-order phase transition between absorbing and active state. We present a numerical calculation of the renormalization group functions in the $\epsilon$-expansion where $\epsilon$ is a deviation from the upper critical dimension $d_c = 4$. Within this procedure anomalous dimensions $\gamma$ are expressed in terms of irreducible renormalized Feynman diagrams and thus the calculation of renormalization constants could be entirely skipped. The renormalization group is included by means of the $R$ operation, and for computational purposes we choose the null momentum subtraction scheme.