Critical motility-induced phase separation belongs to the Ising universality class

TL;DR

This paper demonstrates that critical motility-induced phase separation (MIPS) in self-propelled particles with volume exclusion belongs to the well-known Ising universality class, indicating no new universality class arises from this non-equilibrium transition.

Contribution

The study shows that critical MIPS shares the universality class with the equilibrium Ising model, clarifying its fundamental nature.

Findings

Critical MIPS belongs to the Ising universality class.

The phase transition in MIPS exhibits Ising-like critical behavior.

MIPS at criticality does not define a new universality class.

Abstract

A collection of self-propelled particles with volume exclusion interactions can exhibit the phenomenology of gas-liquid phase separation, known as motility-induced phase separation (MIPS). The non-equilibrium nature of the system is fundamental to the phase transition, however, it is unclear whether MIPS at criticality contributes a novel universality class to non-equilibrium physics. We demonstrate here that this is not the case by showing that a generic critical MIPS belongs to the Ising universality class with conservative dynamics.