{
  "id": "2112.04513",
  "version": "v2",
  "published": "2021-12-08T19:00:03.000Z",
  "updated": "2022-08-27T19:51:51.000Z",
  "title": "Lepton-Flavor-Violating ALPs at the Electron-Ion Collider: A Golden Opportunity",
  "authors": [
    "Hooman Davoudiasl",
    "Roman Marcarelli",
    "Ethan T. Neil"
  ],
  "comment": "16 pages, 4 figures. v2: corrected EIC ion-mode luminosity projection; significant updates to analysis",
  "categories": [
    "hep-ph",
    "hep-ex",
    "nucl-ex"
  ],
  "abstract": "Axion-like particles (ALPs) arise in a variety of theoretical contexts and can, in general, mediate flavor violating interactions and parity non-conservation. We consider lepton flavor violating ALPs with GeV scale or larger masses which may, for example, arise in composite dark sector models. We show that a future Electron-Ion Collider (EIC) can uncover or constrain such ALPs via processes of the type $e \\, A_Z \\to \\tau \\, A_Z\\, a$, where $A_Z$ is a nucleus of charge $Z$ and $a$ is an ALP in the range $m_\\tau \\leq m_a \\lesssim 20$ GeV. The production of the ALP can have a large $Z^2$ enhancement from low $Q^2$ electromagnetic scattering of the electron from a heavy ion. Using the gold nucleus ($Z=79$) as an example, we show that the EIC can explore $e-\\tau$ flavor violation, mediated by GeV-scale ALPs, well beyond current limits. Importantly, the EIC reach for this interaction is not sensitive to the lepton-flavor conserving ALP couplings, whose possible smallness can render searches using $\\tau$ decays ineffective. We also discuss how the EIC electron beam polarization can provide a powerful tool for investigating parity violating ALPs.",
  "revisions": [
    {
      "version": "v2",
      "updated": "2022-08-27T19:51:51.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "electron-ion collider",
      "golden opportunity",
      "lepton-flavor-violating alps",
      "eic electron beam polarization",
      "composite dark sector models"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 16,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}