{
  "abstract": "Cosmic birefringence, the rotation of the polarization plane of cosmic microwave background (CMB) photons, provides an intriguing probe of physics beyond the Standard Model. In this paper, we investigate a vector Chern-Simons coupling between the neutrino current and photons as a possible origin of isotropic cosmic birefringence. Firstly, we perform the first analysis of anisotropic cosmic birefringence induced by the neutrino current. We find that the anisotropic signal sourced by lepton-number isocurvature fluctuations can be important on large scales, whereas on small scales, the anisotropic signal induced by gravitational effects becomes dominant comparing with the axion-like particle (ALP) scenario. Secondly, we show that a large lepton asymmetry generated through the Affleck-Dine mechanism can successfully account for the observed isotropic birefringence, and discuss its possible connection to the recently reported low helium-4 abundances in Subaru EMPRESS and Atacama Cosmology Telescope (ACT).",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.09748",
  "author_total": 2,
  "authors": [
    {
      "name": "Kentaro Kasai"
    },
    {
      "name": "Ippei Obata"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/8dgagy3gkap66.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.09748",
  "fulltext_url": null,
  "id": "8dgagy3gkap66",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.09748",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.CO"
    ],
    [
      "arxiv",
      "hep-ph"
    ],
    [
      "openalex",
      "3103|Cosmology and Gravitation Theories"
    ]
  ],
  "openalex": "W7220901506",
  "pdf_url": "https://arxiv.org/pdf/2610.09748",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-28",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/8dgagy3gkap66.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:36:22Z",
      "native_id": "2610.09748",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.09748"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "physics",
      "origin": "arxiv:hep-ph",
      "subfield": "high-energy"
    }
  ],
  "title": "Cosmic Birefringence from Large Lepton Asymmetry",
  "title_text": "Cosmic Birefringence from Large Lepton Asymmetry",
  "type": "preprint",
  "updated_at": "2026-11-01T12:20:44Z",
  "url": "https://research.draconitic.com/paper/8dgagy3gkap66",
  "venue": "arXiv",
  "versions": []
}