Finite scale singularity in the renormalization group flow of a reaction-diffusion system

TL;DR

This paper investigates the critical behavior of a reaction-diffusion system using nonperturbative renormalization group methods, revealing a finite-scale singularity and suggesting possible universality classes.

Contribution

It introduces a nonperturbative approach to analyze the PCPD, uncovering a finite-scale singularity and the emergence of new universality classes.

Findings

Perturbation theory fails due to nonanalyticity at finite scale

Dynamically generated terms allow flow continuation

Critical behavior may belong to known or new universality classes

Abstract

We study the nonequilibrium critical behavior of the pair contact process with diffusion (PCPD) by means of nonperturbative functional renormalization group techniques. We show that usual perturbation theory fails because the effective potential develops a nonanalyticity at a finite length scale: Perturbatively forbidden terms are dynamically generated and the flow can be continued once they are taken into account. Our results suggest that the critical behavior of PCPD can be either in the directed percolation or in a new (conjugated) universality class.