Using field-theoretic renormalization group methods we calculate the equation of state for non-equilibrium systems belonging to the universality class of directed percolation (Gribov process) to second order in epsilon = 4-d. By introducing a parametric representation the result can be written to this order in a very simple form. We use our result to obtain a universal amplitude ratio to second order in epsilon.
Cite
@article{arxiv.cond-mat/9810309,
title = {Equation of state for directed percolation},
author = {H. K. Janssen and Ue. Kutbay and K. Oerding},
journal= {arXiv preprint arXiv:cond-mat/9810309},
year = {2009}
}