{
  "id": "1303.1773",
  "version": "v3",
  "published": "2013-03-07T18:18:29.000Z",
  "updated": "2013-08-29T11:45:57.000Z",
  "title": "Constraints on Disformal Couplings from the Properties of the Cosmic Microwave Background Radiation",
  "authors": [
    "Carsten van de Bruck",
    "Jack Morrice",
    "Susan Vu"
  ],
  "comment": "5 pages, RevTeX, 2 figures; paper completely rewritten to accommodate new results. Includes now discussions of: multiple disformal couplings, kinetic theory, effective chemical potential, temperature-redshift relation and frame-dependence of equation of state",
  "categories": [
    "astro-ph.CO",
    "gr-qc",
    "hep-th"
  ],
  "abstract": "Certain modified gravity theories predict the existence of an additional, non-conformally coupled scalar field. A disformal coupling of the field to the Cosmic Microwave Background (CMB) is shown to affect the evolution of the energy density in the radiation fluid and produces a modification of the distribution function of the CMB, which vanishes if photons and baryons couple in the same way to the scalar. We find the constraints on the couplings to matter and photons coming from the measurement of the CMB temperature evolution and from current upper limits on the $\\mu$--distortion of the CMB spectrum. We also point out that the measured equation of state of photons differs from $w_\\gamma = 1/3$ in the presence of disformal couplings.",
  "revisions": [
    {
      "version": "v3",
      "updated": "2013-08-29T11:45:57.000Z"
    }
  ],
  "analyses": {
    "subjects": [
      "98.70.Vc",
      "04.50.Kd",
      "95.36.+x"
    ],
    "keywords": [
      "cosmic microwave background radiation",
      "disformal coupling",
      "constraints",
      "properties",
      "current upper limits"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1103/PhysRevLett.111.161302",
      "journal": "Physical Review Letters",
      "year": 2013,
      "month": "Oct",
      "volume": 111,
      "number": 16,
      "pages": 161302
    },
    "note": {
      "typesetting": "RevTeX",
      "pages": 5,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1222830,
      "adsabs": "2013PhRvL.111p1302V"
    }
  }
}