{
  "id": "1511.06737",
  "version": "v1",
  "published": "2015-11-20T19:53:46.000Z",
  "updated": "2015-11-20T19:53:46.000Z",
  "title": "Helicity Evolution at Small-x",
  "authors": [
    "Yuri V. Kovchegov",
    "Daniel Pitonyak",
    "Matthew D. Sievert"
  ],
  "comment": "33 pages, 20 figures",
  "categories": [
    "hep-ph"
  ],
  "abstract": "We construct small-x evolution equations which can be used to calculate quark and anti-quark helicity TMDs and PDFs, along with the $g_1$ structure function. These evolution equations resum powers of $\\alpha_s \\, \\ln^2 (1/x)$ in the polarization-dependent evolution along with the powers of $\\alpha_s \\, \\ln (1/x)$ in the unpolarized evolution which includes saturation effects. The equations are written in an operator form in terms of polarization-dependent Wilson line-like operators. While the equations do not close in general, they become closed and self-contained systems of non-linear equations in the large-$N_c$ and large-$N_c \\, \\& \\, N_f$ limits. As a cross-check, in the ladder approximation, our equations map onto the same ladder limit of the infrared evolution equations for $g_1$ structure function derived previously by Bartels, Ermolaev and Ryskin.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2015-11-20T19:53:46.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "helicity evolution",
      "construct small-x evolution equations",
      "evolution equations resum powers",
      "structure function",
      "polarization-dependent wilson line-like operators"
    ],
    "publication": {
      "doi": "10.1007/JHEP01(2016)072",
      "journal": "Journal of High Energy Physics",
      "year": 2016,
      "month": "Jan",
      "volume": 2016,
      "pages": 72
    },
    "note": {
      "typesetting": "TeX",
      "pages": 33,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2016JHEP...01..072K",
      "inspire": 1405745
    }
  }
}