{
  "id": "0808.2576",
  "version": "v3",
  "published": "2008-08-19T11:52:11.000Z",
  "updated": "2008-11-21T01:55:27.000Z",
  "title": "Measurement of $B^0\\toπ^+π^-π^+π^-$ Decays and Search for $B^0\\toρ^0ρ^0$",
  "authors": [
    "The Belle Collaboration",
    "C. -C. Chiang"
  ],
  "comment": "6 pages, 2 figures. Submitted to PRD(RC)",
  "journal": "Phys.Rev.D78:111102,2008",
  "doi": "10.1103/PhysRevD.78.111102",
  "categories": [
    "hep-ex"
  ],
  "abstract": "We report on a search for the decay $B^0\\to\\rho^0\\rho^0$ and other charmless modes with a $\\pi^+\\pi^-\\pi^+\\pi^-$ final state, including $B^0\\to\\rho^0\\pi^+\\pi^-$, non-resonant $B^0\\to 4\\pi^{\\pm}$, $B^0\\to\\rho^0f_0(980)$, $B^0\\to f_0(980)f_0(980)$ and $B^0\\to f_0(980)\\pi^+\\pi^-$. These results are obtained from a data sample containing 657 million $B \\overline B$ pairs collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. We set an upper limit on $\\mathcal{B}(B^0\\to\\rho^0\\rho^0)$ of $1.0\\times 10^{-6}$ at the 90% confidence level (C.L.). From our $B^0\\to\\rho^0\\rho^0$ measurement and an isospin analysis, we determine the Cabibbo-Kobayashi-Maskawa phase $\\phi_2$ to be $91.7 \\pm 14.9$ degrees. We find excesses in $B^0\\to \\rho^0\\pi^+\\pi^-$ and non-resonant $B^0\\to 4\\pi^{\\pm}$ with 1.3$\\sigma$ and 2.5$\\sigma$ significance, respectively. The corresponding branching fractions are less than $12.0 \\times 10^{-6}$ and $19.3 \\times 10^{-6}$ at the 90% C.L. In addition, we set 90% C.L. upper limits as follows: $\\mathcal{B}(B^0\\to\\rho^0f_0(980))< 0.3 \\times 10^{-6}$, $\\mathcal{B}(B^0\\to f_0(980)f_0(980))< 0.1 \\times 10^{-6}$, and $\\mathcal{B}(B^0\\to f_0(980)\\pi^+\\pi^-)< 3.8 \\times 10^{-6}$.",
  "revisions": [
    {
      "version": "v3",
      "updated": "2008-11-21T01:55:27.000Z"
    }
  ],
  "analyses": {
    "subjects": [
      "11.30.Er",
      "14.40.Nd",
      "12.15.Hh",
      "13.25.Hw"
    ],
    "keywords": [
      "measurement",
      "upper limit",
      "belle detector",
      "kekb asymmetric-energy",
      "final state"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "publisher": "APS",
      "journal": "Physical Review D",
      "year": 2008,
      "month": "Dec",
      "volume": 78,
      "number": 11,
      "pages": 111102
    },
    "note": {
      "typesetting": "TeX",
      "pages": 6,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 793389,
      "adsabs": "2008PhRvD..78k1102C"
    }
  }
}