{
  "id": "1609.08514",
  "version": "v1",
  "published": "2016-09-27T16:05:31.000Z",
  "updated": "2016-09-27T16:05:31.000Z",
  "title": "Extraction of the $π^+π^-$ Subsystem in Diffractively Produced $π^-π^+π^-$ at COMPASS",
  "authors": [
    "Fabian Krinner"
  ],
  "comment": "Proceedings for the MENU 2016 conference from 25 July 2016 to 30 July 2016, 6 pages, 15 figures",
  "categories": [
    "hep-ex"
  ],
  "abstract": "The COMPASS experiment at CERN has collected a large data sample of 50 million diffractively produced $\\pi^-\\pi^+\\pi^-$ events using a $190\\,$GeV$/c$ negatively charged hadron beam. The partial-wave analysis (PWA) of these high-precision data reveals previously unseen details. The PWA, which is currently limited by systematic uncertainties, is based on an isobar model, where multi-particle decays are described as subsequent two-body decays and where a prior-knowledge parametrization for the intermediate two-pion resonances has to be assumed -- usually a Breit-Wigner amplitude -- thus increasing systematic uncertainties, due to the concrete choice of the parametrization. We present a novel method, which allows to extract isobar amplitudes directly from the data in a less biased way. The focus lies on the scalar $\\pi^+\\pi^-$ subsystem, where a previous analysis found a signal for a new axial-vector state $a_1(1420)$ decaying into $f_0(980)\\pi$.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2016-09-27T16:05:31.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "extraction",
      "large data sample",
      "extract isobar amplitudes",
      "intermediate two-pion resonances",
      "subsequent two-body decays"
    ],
    "tags": [
      "conference paper"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 6,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}