{
  "id": "2109.10093",
  "version": "v1",
  "published": "2021-09-21T10:55:03.000Z",
  "updated": "2021-09-21T10:55:03.000Z",
  "title": "Probing the $L_μ$-$L_τ$ Gauge Boson at the MUonE Experiment",
  "authors": [
    "Kento Asai",
    "Koichi Hamaguchi",
    "Natsumi Nagata",
    "Shih-Yen Tseng",
    "Juntaro Wada"
  ],
  "comment": "6pages, 3 figures",
  "categories": [
    "hep-ph",
    "hep-ex"
  ],
  "abstract": "We discuss the prospects of probing the $L_\\mu - L_\\tau$ gauge boson at the MUonE experiment. The $L_\\mu - L_\\tau$ gauge boson $Z^\\prime$ with a mass of $\\lesssim 200$ MeV, which can explain the discrepancy between the measured value of the muon $g-2$ and the value calculated in the Standard Model, can be produced at the MUonE experiment through the process $\\mu e \\to \\mu e Z^\\prime$. The $Z^\\prime$ in the final state decays into a pair of neutrinos, and therefore we cannot observe the decay of $Z^\\prime$ directly. It is, however, still possible to probe this signature by searching for events with a large scattering angle of muon and a less energetic final-state electron. The background events coming from the elastic scattering $\\mu e \\to \\mu e$ as well as radiative process $\\mu e \\to \\mu e \\gamma$ can be removed by the kinematical cuts on the muon scattering angle and the electron energy, in addition to a photon veto. The background events from the electroweak process $\\mu e \\to \\mu e \\nu \\bar{\\nu}$ are negligible. With our selection criteria, the number of signal events $\\mu e \\to \\mu e Z^\\prime$ is found to be as large as $\\sim 10^3$ in the parameter region motivated by the muon $g-2$ discrepancy. It is, therefore, quite feasible to probe the $L_\\mu - L_\\tau$ gauge boson at the MUonE experiment -- without introducing additional devices -- and we strongly recommend recording the events relevant to this $Z^\\prime$ production process.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2021-09-21T10:55:03.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "muone experiment",
      "gauge boson",
      "background events",
      "final state decays",
      "energetic final-state electron"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 6,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}