{
  "id": "1604.03327",
  "version": "v1",
  "published": "2016-04-12T10:12:01.000Z",
  "updated": "2016-04-12T10:12:01.000Z",
  "title": "Axion Inflation with an SU(2) Gauge Field: Detectable Chiral Gravity Waves",
  "authors": [
    "Azadeh Maleknejad"
  ],
  "comment": "34 pages, 8 figures",
  "categories": [
    "hep-ph",
    "hep-th"
  ],
  "abstract": "We study a single field axion inflation model in the presence of an SU(2) gauge field with a small vev. In order to make the analysis as model-independent as possible, we consider an arbitrary potential for the axion that is able to support the slow-roll inflation. The gauge field is coupled to the axion with a Chern-Simons interaction $\\frac{\\lambda}{f}F_{\\mu\\nu}^a\\tilde F_a^{\\mu\\nu}$ where $\\frac{\\lambda}{f}\\sim\\mathcal{O}(10)$. It has a negligible effect on the background evolution, $\\frac{\\rho_{_{\\rm YM}}}{M_{\\rm Pl}^2H^2}\\lesssim\\epsilon^2$. However, its quantum fluctuations make a significant contribution to the cosmic perturbation. In particular, the gauge field has a spin-2 fluctuation which explicitly breaks the parity between the left- and right-handed polarization states. The chiral tensor modes are linearly coupled to the gravitational waves and lead to a circularly polarized tensor power spectrum comparable to the unpolarized vacuum power spectrum. Moreover, the scalar sector is modified by the linear scalar fluctuations of the gauge field. Since the spin-0 and spin-2 fluctuations of the SU(2) gauge field are independent, the gauge field can, at the same time, generate a detectable chiral gravitational wave signal and have a negligible contribution to the scalar fluctuations, in agreement with the current CMB observations.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2016-04-12T10:12:01.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "gauge field",
      "detectable chiral gravity waves",
      "field axion inflation model",
      "chiral gravitational wave signal",
      "polarized tensor power spectrum"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 34,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2016arXiv160403327M"
    }
  }
}