{
  "id": "hep-ph/9906444",
  "version": "v1",
  "published": "1999-06-23T01:28:57.000Z",
  "updated": "1999-06-23T01:28:57.000Z",
  "title": "Twist-4 contribution to unpolarized structure functions F_L and F_2 from instantons",
  "authors": [
    "B. Dressler",
    "M. Maul",
    "C. Weiss"
  ],
  "comment": "38 pages, LaTeX. 4 figures included using epsf",
  "journal": "Nucl.Phys. B578 (2000) 293-325",
  "doi": "10.1016/S0550-3213(00)00024-9",
  "categories": [
    "hep-ph"
  ],
  "abstract": "We compute in the instanton vacuum the nucleon matrix elements of the twist-4 QCD operators describing power corrections to the second moments of the unpolarized structure functions, F_L and F_2. Our approach takes into account the leading contribution in the packing fraction of the instanton medium, rho / R << 1. Parametrically leading are the matrix elements of a twist-4 quark-gluon operator, which are of the order of the inverse instanton size, 1/rho^2 = (600 MeV)^2. The matrix elements of the four-fermion (diquark) operators are suppressed by a factor (rho / R)^4 and numerically small. These results are in agreement with the pattern of phenomenological 1/Q^2-corrections to R = sigma_L / sigma_T and F_2 found in QCD fits to the data. In particular, the rise of R at low Q^2 can be obtained from instanton-type vacuum fluctuations at a low scale.",
  "revisions": [
    {
      "version": "v1",
      "updated": "1999-06-23T01:28:57.000Z"
    }
  ],
  "analyses": {
    "subjects": [
      "13.60.Hb",
      "12.38.Lg",
      "11.15.Kc",
      "12.39.Ki"
    ],
    "keywords": [
      "unpolarized structure functions",
      "contribution",
      "qcd operators describing power corrections",
      "nucleon matrix elements",
      "instanton-type vacuum fluctuations"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "publisher": "Elsevier",
      "journal": "Nucl. Phys. B"
    },
    "note": {
      "typesetting": "LaTeX",
      "pages": 38,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 502183
    }
  }
}