{
  "id": "hep-ph/0307057",
  "version": "v2",
  "published": "2003-07-04T13:29:15.000Z",
  "updated": "2003-12-17T16:05:05.000Z",
  "title": "Gauge checks, consistency of approximation schemes and numerical evaluation of realistic scattering amplitudes",
  "authors": [
    "Christian Schwinn"
  ],
  "comment": "LaTeX2e,170 pages (based on PhD thesis), ps and feynmp figures included, typos corrected",
  "categories": [
    "hep-ph"
  ],
  "abstract": "We discuss both theoretical tools to verify gauge invariance in numerical calculations of cross sections and the consistency of approximation schemes used in realistic calculations. A finite set of Ward Identities for 4 point scattering amplitudes is determined, that is sufficient to verify the correct implementation of Feynman rules of a spontaneously broken gauge theory in a model independent way. These identities have been implemented in the matrix element generator O'Mega and have been used to verify the implementation of the complete Standard Model in R_\\xi gauge. The consistency of approximation schemes in tree level calculations is discussed in the last part of this work. We determine the gauge invariance classes of spontaneously broken gauge theories, providing a new proof for the formalism of gauge and flavor flips. The schemes for finite width effects that have been implemented in O'Mega are reviewed. As a comparison with existing calculations, we study the consistency of these schemes in the process e^-e^+\\to e^- \\bar \\nu_e u\\bar d. The violations of gauge invariance caused by the introduction of running coupling constants are analyzed.",
  "revisions": [
    {
      "version": "v2",
      "updated": "2003-12-17T16:05:05.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "approximation schemes",
      "realistic scattering amplitudes",
      "gauge checks",
      "consistency",
      "spontaneously broken gauge theory"
    ],
    "tags": [
      "dissertation"
    ],
    "publication": {
      "journal": "Ph.D. Thesis",
      "year": 2003,
      "month": "Jul"
    },
    "note": {
      "typesetting": "LaTeX",
      "pages": 170,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 622796,
      "adsabs": "2003PhDT.......324S"
    }
  }
}