Comment on ``Phase Transitions in Systems of Self-Propelled Agents and Related Network Models''

TL;DR

This paper argues that the transition to collective motion in Vicsek-like systems remains discontinuous at high velocities, suggesting that the network models studied previously are only a special case at large velocities.

Contribution

It clarifies the nature of phase transitions in Vicsek-like models, showing that they stay discontinuous at high velocities, and positions network models as a singular limit.

Findings

Transition remains discontinuous at large velocities

Network models are a singular limit of Vicsek systems

High velocity effects on phase transition are clarified

Abstract

In this comment we show that the transition to collective motion in Vicsek-like systems with angular noise remain discontinuous for large velocity values. Thus, the networks studied by Aldana {\et al.} [Phys. Rev. Lett. {\bf 98}, 095702 (2007)] at best constitute a singular, large velocity limit of these systems.