{
  "id": "hep-ex/9907005",
  "version": "v1",
  "published": "1999-07-07T22:19:01.000Z",
  "updated": "1999-07-07T22:19:01.000Z",
  "title": "First observation of the $φ\\toπ^+π^-γ$ decay",
  "authors": [
    "CMD-2 Collaboration"
  ],
  "comment": "16 pages, 10 figures, Submitted to Phys. Lett. B",
  "journal": "Phys.Lett.B462:371,1999",
  "doi": "10.1016/S0370-2693(99)00919-3",
  "categories": [
    "hep-ex"
  ],
  "abstract": "Radiative decays of the $\\phi$ meson have been studied using a data sample of about 20 million $\\phi$ decays collected by the CMD-2 detector at VEPP-2M collider in Novosibirsk. From selected $e^+e^-\\to\\pi^{+}\\pi^{-}\\gamma$ events the $\\phi\\to\\pi^{+}\\pi^{-}\\gamma$ decay has been observed for the first time. \\par Under the assumption that the intermediate $f_{0}(980)\\gamma$ state dominates in the $\\phi \\to \\pi^+\\pi^-\\gamma$ decay, the corresponding branching ratio is $Br(\\phi\\to f_{0}(980)\\gamma)=(1.93\\pm 0.46\\pm 0.50)\\times10^{-4}$. \\par Selected $e^+e^-\\to\\mu^+\\mu^-\\gamma$ events were used to obtain $Br(\\phi\\to\\mu^+\\mu^-\\gamma) =(1.43\\pm 0.45\\pm 0.14)\\times10^{-5}$ for $E_{\\gamma}>20$ MeV. \\par Using the same data sample, upper limits at 90% CL have been obtained for the C-violating decay of the $\\phi$: $Br(\\phi\\to\\rho\\gamma) < 1.2\\times10^{-5}$; and for the P- and CP-violating decay of the $\\eta$: \\par $Br(\\eta\\to\\pi^+\\pi^-) < 3.3\\times10^{-4}$.",
  "revisions": [
    {
      "version": "v1",
      "updated": "1999-07-07T22:19:01.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "first observation",
      "data sample",
      "state dominates",
      "first time",
      "upper limits"
    ],
    "tags": [
      "journal article"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 16,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 503231
    }
  }
}