Phase separation and emergence of order in a one-dimension

L. BARBERIS; F. PERUANI

La Plata

Workshop; Statistical Mechanics y Swarming Behavior; 2019

In this presentation we study a one-dimensional system of self-propelled particles, where the state of the particlesis given by a moving direction (left or right), spin-like variable, and their position.Particles interact by short-ranged, spring-like attractive forces in an asymetrycal range Ω, and do not possessspin-spin interactions (i.e., velocity alignment) Also, particles spontaneously flip their direction according to α = exp − n β i , where β is a gaussian noise and n ithe neighbor number of particle i.We show due to the absence of the action-reaction symmetry, there exists an intimate link between phase separationand the formation of highly coherent, spatially localized, moving flocks (i.e., collective motion).We prove the existence of two fundamentally different types of active phase separation which we refer to as neutralphase separation, Fig 1(a); and polar phase separation, Fig 1(b). The first one is also subdivided in two classescharactrized by different critical exponents.These results are of key importance to understand that in active matter there exist several phase-separation classesand that the emergence of polar, self-organized patterns (i.e., flocks) does not require the presence of a velocityalignment