{
  "id": "1702.01497",
  "version": "v1",
  "published": "2017-02-06T05:07:43.000Z",
  "updated": "2017-02-06T05:07:43.000Z",
  "title": "Cornering the $L_μ-L_τ$ gauge boson at Belle-II",
  "authors": [
    "Takeshi Araki",
    "Shihori Hoshino",
    "Toshihiko Ota",
    "Joe Sato",
    "Takashi Shimomura"
  ],
  "comment": "10 pages, 10 figures",
  "categories": [
    "hep-ph",
    "hep-ex"
  ],
  "abstract": "We discuss the feasibility of detecting the gauge boson of the $U(1)_{L_{\\mu}-L_{\\tau}}$ symmetry, which possesses a mass in the range between MeV and GeV, at the Belle-II experiment. The kinetic mixing between the new gauge boson $Z'$ and photon is forbidden at the tree level and is radiatively induced. The leptonic force mediated by such a light boson is motivated by the discrepancy in muon anomalous magnetic moment and also the gap in the energy spectrum of cosmic neutrino. Defining the process $e^{+} e^{-} \\rightarrow \\gamma Z' \\rightarrow \\gamma \\nu \\bar{\\nu}~(missing~energy)$ to be the signal, we estimate the numbers of the signal and the background events and show the parameter region to which the Belle-II experiment will be sensitive. The signal process in the $L_{\\mu}-L_{\\tau}$ model is enhanced with a light $Z'$, which is a characteristic feature differing from the dark photon models with a constant kinetic mixing. We find that the Belle-II experiment with the design luminosity will be sensitive to the $Z'$ with the mass $M_{Z'} \\lesssim 1 $ GeV and the new gauge coupling $g_{Z'} \\gtrsim 8\\cdot 10^{-4}$, which covers a half of the unconstrained parameter region that explains the discrepancy in muon anomalous magnetic moment. The possibilities to improve the significance of the detection are also discussed.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2017-02-06T05:07:43.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "gauge boson",
      "muon anomalous magnetic moment",
      "belle-ii experiment",
      "parameter region",
      "dark photon models"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 10,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}