Short-time dynamics in active systems: the Vicsek model

TL;DR

This paper investigates the short-time dynamics of the Vicsek model with vector noise, demonstrating its effectiveness in identifying phase transition types, critical points, and exponents in active, non-equilibrium systems.

Contribution

It shows that short-time dynamics methods, traditionally used in equilibrium systems, are applicable to active systems like the Vicsek model, revealing their phase transition properties.

Findings

STD can distinguish continuous and discontinuous transitions.

Critical points and exponents can be determined from STD.

STD phenomenology is similar in equilibrium and active systems.

Abstract

We study the short-time dynamics (STD) of the Vicsek model with vector noise. The study of STD has proved to be very useful in the determination of the critical point, critical exponents, and spinodal points in equilibrium phase transitions. Here we aim to test its applicability in active systems. We find that, despite the essential non-equilibrium characteristics of the VM (absence of detailed balance, activity), the STD presents qualitatively the same phenomenology as in equilibrium systems. From the STD one can distinguish whether the transition is continuous or discontinuous (which we have checked also computing the Binder cumulant). When the transition is continuous, one can determine the critical point and the critical exponents.