{
  "abstract": "A bstract : We consider the coupling of axions to gauge bosons in higher-dimensional Grand Unified Theories (GUT) inspired by string theory constructions with D-branes on orbifold singularities, the so-called orbifold GUTs. Due to their topological properties, axion couplings to gauge bosons are independent of the gauge symmetry reduction mechanism and the background geometry — they only depend on the embedding of the SM into the UV gauge group. There are two kinds of axions in this class of theories: axions coming from gauge fields in the bulk and axions localised on the boundaries. The axion-photon coupling for the bulk axions coincide with the results from 4-dimensional GUTs, where axions which couple to photons necessarily couple also to QCD. The brane-localised axions can couple to photons independently of the QCD coupling, but if gauge couplings are approximately unified, they have a much more severe quality problem. We show that in generic UV completions they are expected to get large masses from instantons on the boundaries. This means that the ratio g aγγ / m a is below (or equal to) the QCD axion value for all axions in orbifold GUTs, as is the case for unified theories in 4d.",
  "abstract_shown": true,
  "affiliations": [
    "University of California",
    "University of Oxford",
    "Harvard University",
    "Theoretical Physics Department, CERN"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 3,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Prateek Agrawal",
      "orcid": "0000-0001-9947-0632"
    },
    {
      "affs": [
        2
      ],
      "name": "Michael Nee",
      "orcid": "0000-0003-1345-3941"
    },
    {
      "affs": [
        1,
        3
      ],
      "name": "Mario Reig",
      "orcid": "0000-0001-6815-5605"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/dvhwnnzsgx5qh.bib",
  "cited_by": 2,
  "doi": "10.1007/jhep10(2026)032",
  "fulltext_url": null,
  "id": "dvhwnnzsgx5qh",
  "issns": [
    "1029-8479"
  ],
  "landing_url": "https://link.springer.com/10.1007/JHEP10(2026)032",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "3106|Particle physics theoretical and experimental studies"
    ]
  ],
  "openalex": "W7108224419",
  "pdf_url": "https://link.springer.com/content/pdf/10.1007/JHEP10(2026)032.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-02",
  "publisher": "Springer Science and Business Media LLC",
  "ris": "https://research.draconitic.com/paper/dvhwnnzsgx5qh.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:01Z",
      "native_id": "10.1007/jhep10(2026)032",
      "source": "crossref",
      "url": "https://link.springer.com/10.1007/JHEP10(2026)032"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "openalex:3106|Particle physics theoretical and experimental studies",
      "subfield": "high-energy"
    }
  ],
  "title": "Axion couplings in orbifold GUTs",
  "title_text": "Axion couplings in orbifold GUTs",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:18:01Z",
  "url": "https://research.draconitic.com/paper/dvhwnnzsgx5qh",
  "venue": "Journal of High Energy Physics",
  "versions": []
}