{
  "id": "2007.04291",
  "version": "v1",
  "published": "2020-07-08T17:38:30.000Z",
  "updated": "2020-07-08T17:38:30.000Z",
  "title": "Large Neutrino Magnetic Moments in the Light of Recent Experiments",
  "authors": [
    "K. S. Babu",
    "Sudip Jana",
    "Manfred Lindner"
  ],
  "comment": "40 pages+references, 19 figures",
  "categories": [
    "hep-ph",
    "astro-ph.SR",
    "hep-ex"
  ],
  "abstract": "The excess in electron recoil events reported recently by the XENON1T experiment may be interpreted as evidence for a sizable transition magnetic moment $\\mu_{\\nu_e\\nu_\\mu}$ of Majorana neutrinos. We show the consistency of this scenario when a single component transition magnetic moment takes values $\\mu_{\\nu_e\\nu_\\mu} \\in(1.91 - 3.96) \\times 10^{-11} \\mu_B$. Such a large value usually leads to unacceptably large neutrino masses. In this paper we show that new symmetries systematically solve this problem and we demonstrate this by discussing a few examples. We first revive and then propose a simplified model based on $SU(2)_H$ horizontal symmetry which solves this problem. Owing to the difference in their Lorentz structures, in the $SU(2)_H$ symmetric limit, $m_\\nu$ vanishes while $\\mu_{\\nu_e\\nu_\\mu}$ is nonzero. Our simplified model is based on an approximate $SU(2)_H$, which we also generalize to a three family $SU(3)_H$-symmetry. Collider and low energy tests of these models are analyzed. We also suggest a mechanism to evade stringent astrophysical limits on neutrino magnetic moments arising from stellar evolution by inducing a medium-dependent mass for the neutrino. We have also analyzed implications of the XENON1T data for the Zee model and its extensions which naturally generate a large $\\mu_{\\nu_e\\nu_\\mu}$ with suppressed $m_\\nu$ via a spin symmetry mechanism, but found that the induced $\\mu_{\\nu_e\\nu_\\mu}$ is not large enough to explain recent data.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2020-07-08T17:38:30.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "large neutrino magnetic moments",
      "single component transition magnetic moment",
      "experiment",
      "sizable transition magnetic moment",
      "unacceptably large neutrino masses"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 40,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}