{
  "id": "1406.6088",
  "version": "v3",
  "published": "2014-06-23T20:50:28.000Z",
  "updated": "2015-04-02T15:18:35.000Z",
  "title": "From Phase to Micro-Phase Separation in Flocking Models: The Essential Role of Non-Equilibrium Fluctuations",
  "authors": [
    "Alexandre P. Solon",
    "Hugues Chaté",
    "Julien Tailleur"
  ],
  "comment": "5 p., 5 fig.. Supplementary material: 7 movies",
  "journal": "Phys. Rev. Lett. 114, 068101 (2015)",
  "doi": "10.1103/PhysRevLett.114.068101",
  "categories": [
    "cond-mat.stat-mech",
    "cond-mat.soft"
  ],
  "abstract": "We show that the flocking transition in the Vicsek model is best understood as a liquid-gas transition, rather than an order-disorder one. The full phase separation observed in flocking models with Z2 rotational symmetry is, however, replaced by a microphase separation leading to a smectic arrangement of traveling ordered bands. Remarkably, continuous deterministic descriptions do not account for this difference, which is only recovered at the fluctuating hydrodynamics level. Scalar and vectorial order parameters indeed produce different types of number fluctuations, which we show to be essential in selecting the inhomogeneous patterns. This highlights an unexpected role of fluctuations in the selection of flock shapes.",
  "revisions": [
    {
      "version": "v2",
      "updated": "2014-06-25T09:35:40.000Z",
      "abstract": "We show that the flocking transition in the Vicsek model is best understood as a liquid-gas transition in the canonical ensemble leading to metastability, hysteresis and (micro) phase coexistence between a disordered gas and a smectic arrangement of traveling liquid bands. This is in contrast with the bulk phase separation exhibited by the active Ising model, a flocking model with discrete symmetry. We find that while (deterministic) hydrodynamic equations cannot explain this difference, their stochastic counterparts do: scalar and vectorial order parameter produce different types of number fluctuations, which are essential in selecting the phase-separated patterns.",
      "journal": null,
      "doi": null
    },
    {
      "version": "v3",
      "updated": "2015-04-02T15:18:35.000Z"
    }
  ],
  "analyses": {
    "subjects": [
      "87.23.Cc",
      "05.65.+b",
      "47.27.ed",
      "47.54.-r"
    ],
    "keywords": [
      "flocking models",
      "non-equilibrium fluctuations",
      "essential role",
      "micro-phase separation",
      "vectorial order parameters"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "publisher": "APS",
      "journal": "Physical Review Letters",
      "year": 2015,
      "month": "Feb",
      "volume": 114,
      "number": 6,
      "pages": "068101"
    },
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2015PhRvL.114f8101S"
    }
  }
}