{
  "abstract": "We search for gravitational-wave background signals produced by various early Universe processes in the Advanced LIGO O4a dataset, combined with the data from the earlier O1, O2, and O3 (LIGO-Virgo) runs. The absence of detectable signals enables powerful constraints on fundamental physics. We derive gravitational-wave background energy density upper limits from the O1–O4a data to constrain parameters associated with various possible processes in the early Universe: first-order phase transitions, cosmic strings, domain walls, stiff equation of state, axion inflation, second-order scalar perturbations, primordial black hole binaries, and parity violation. In our analyses, the presence of an astrophysical background produced by compact (black hole and neutron star) binary coalescences throughout the Universe is also considered. We address the implications for various cosmological and high-energy physics models based on the obtained parameter constraints. We conclude that LIGO-Virgo data already yield significant constraints on numerous early Universe scenarios.",
  "abstract_shown": true,
  "affiliations": [
    "Max Planck Institute for Gravitational Physics (Albert Einstein Institute), D-14476 Potsdam, Germany",
    "LIGO Hanford Observatory",
    "INFN",
    "Università di Salerno",
    "University of Warwick",
    "Monash University",
    "The Pennsylvania State University",
    "Leibniz Universität Hannover",
    "Max Planck Institute for Gravitational Physics (Albert Einstein Institute), D-30167 Hannover, Germany",
    "University of Wisconsin–Milwaukee",
    "California Institute of Technology",
    "Louisiana State University",
    "Tata Institute of Fundamental Research",
    "Aix-Marseille Université",
    "Université catholique de Louvain",
    "Queen Mary University of London",
    "University of California",
    "University of Minnesota",
    "Instituto Nacional de Pesquisas Espaciais",
    "Université Paris Cité",
    "Università di Roma Tor Vergata",
    "Universiteit Antwerpen",
    "National Astronomical Observatory of Japan",
    "Friedrich-Schiller-Universität Jena",
    "INFN Sezione di Torino",
    "Università degli Studi di Genova",
    "Université Savoie Mont Blanc",
    "Università di Napoli “Federico II,”",
    "Cardiff University",
    "Australian National University",
    "Massachusetts Institute of Technology",
    "Maastricht University",
    "Nikhef",
    "Università di Roma “La Sapienza,”",
    "Aix Marseille Université",
    "Université Paris-Saclay",
    "University of Tokyo",
    "Barcelona Institute of Science and Technology",
    "Gran Sasso Science Institute (GSSI)",
    "Laboratori Nazionali del Gran Sasso"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 100,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Adrian Abac",
      "orcid": "0000-0003-4786-2698"
    },
    {
      "affs": [
        1
      ],
      "name": "I. Abouelfettouh"
    },
    {
      "affs": [
        2,
        3
      ],
      "name": "F. Acernese"
    },
    {
      "affs": [
        4
      ],
      "name": "K. Ackley",
      "orcid": "0000-0002-8648-0767"
    },
    {
      "affs": [
        5
      ],
      "name": "Christian Adamcewicz",
      "orcid": "0000-0001-5525-6255"
    },
    {
      "affs": [
        6
      ],
      "name": "S. Adhicary",
      "orcid": "0009-0004-2101-5428"
    },
    {
      "affs": [
        7,
        8
      ],
      "name": "D. Adhikari"
    },
    {
      "affs": [
        9
      ],
      "name": "N. Adhikari",
      "orcid": "0000-0002-4559-8427"
    },
    {
      "affs": [
        10
      ],
      "name": "R. X. Adhikari",
      "orcid": "0000-0002-5731-5076"
    },
    {
      "affs": [
        11
      ],
      "name": "V. K. Adkins"
    },
    {
      "affs": [
        12
      ],
      "name": "Samsuzzaman Afroz",
      "orcid": "0009-0004-4459-2981"
    },
    {
      "affs": [
        13
      ],
      "name": "A. Agapito"
    },
    {
      "affs": [
        14
      ],
      "name": "D. Agarwal",
      "orcid": "0000-0002-8735-5554"
    },
    {
      "affs": [
        15
      ],
      "name": "M. Agathos",
      "orcid": "0000-0002-9072-1121"
    },
    {
      "affs": [
        16
      ],
      "name": "N. Aggarwal"
    },
    {
      "affs": [
        17
      ],
      "name": "S. Aggarwal"
    },
    {
      "affs": [
        18
      ],
      "name": "O. D. Aguiar",
      "orcid": "0000-0003-1432-0008"
    },
    {
      "affs": [
        19
      ],
      "name": "I.-L. Ahrend"
    },
    {
      "affs": [
        2,
        20
      ],
      "name": "L. Aiello",
      "orcid": "0000-0003-2771-8816"
    },
    {
      "affs": [
        21
      ],
      "name": "A. Ain",
      "orcid": "0000-0003-4534-4619"
    },
    {
      "affs": [
        12
      ],
      "name": "P. Ajith",
      "orcid": "0000-0001-7519-2439"
    },
    {
      "affs": [
        22
      ],
      "name": "Tomotada Akutsu",
      "orcid": "0000-0003-0733-7530"
    },
    {
      "affs": [
        23,
        24
      ],
      "name": "Simone Albanesi",
      "orcid": "0000-0001-7345-4415"
    },
    {
      "affs": [
        2,
        25
      ],
      "name": "W. Ali"
    },
    {
      "affs": [
        7,
        8
      ],
      "name": "S. Al-Kershi"
    },
    {
      "affs": [
        26
      ],
      "name": "C. Alléné"
    },
    {
      "affs": [
        2,
        27
      ],
      "name": "A. Allocca",
      "orcid": "0000-0002-5288-1351"
    },
    {
      "affs": [
        28
      ],
      "name": "S. Al-Shammari"
    },
    {
      "affs": [
        29
      ],
      "name": "P. A. Altin",
      "orcid": "0000-0001-8193-5825"
    },
    {
      "affs": [
        30
      ],
      "name": "S. Álvarez-López",
      "orcid": "0009-0003-8040-4936"
    },
    {
      "affs": [
        26
      ],
      "name": "W. Amar"
    },
    {
      "affs": [
        28
      ],
      "name": "O. Amarasinghe"
    },
    {
      "affs": [
        31,
        32
      ],
      "name": "A. Amato",
      "orcid": "0000-0001-9557-651X"
    },
    {
      "affs": [
        2,
        33
      ],
      "name": "F. Amicucci",
      "orcid": "0009-0005-2139-4197"
    },
    {
      "affs": [
        34
      ],
      "name": "C. Amra"
    },
    {
      "affs": [
        10
      ],
      "name": "A. Ananyeva"
    },
    {
      "affs": [
        10
      ],
      "name": "S. B. Anderson",
      "orcid": "0000-0003-2219-9383"
    },
    {
      "affs": [
        10
      ],
      "name": "Warren G. Anderson",
      "orcid": "0000-0003-0482-5942"
    },
    {
      "affs": [
        35
      ],
      "name": "M. Andia",
      "orcid": "0000-0003-3675-9126"
    },
    {
      "affs": [
        36
      ],
      "name": "M. Ando"
    },
    {
      "affs": [
        37
      ],
      "name": "Marc Andrés-Carcasona",
      "orcid": "0000-0002-8738-1672"
    },
    {
      "affs": [
        38,
        39,
        7,
        8
      ],
      "name": "T. Andrić",
      "orcid": "0000-0002-9277-9773"
    },
    {
      "name": "J. Anglin"
    },
    {
      "affs": [
        2
      ],
      "name": "Stefano Ansoldi",
      "orcid": "0000-0002-5613-7693"
    },
    {
      "name": "Javier Mauricio Antelis",
      "orcid": "0000-0003-3377-0813"
    },
    {
      "affs": [
        35
      ],
      "name": "S. Antier",
      "orcid": "0000-0002-7686-3334"
    },
    {
      "name": "M. Aoumi"
    },
    {
      "affs": [
        2
      ],
      "name": "E. Z. Appavuravther"
    },
    {
      "affs": [
        10
      ],
      "name": "S. Appert"
    },
    {
      "name": "S. K. Apple",
      "orcid": "0009-0007-4490-5804"
    },
    {
      "affs": [
        10
      ],
      "name": "Koji Arai",
      "orcid": "0000-0001-8916-8915"
    },
    {
      "affs": [
        36
      ],
      "name": "A. Araya",
      "orcid": "0000-0002-6884-2875"
    },
    {
      "affs": [
        10
      ],
      "name": "M. C. Araya",
      "orcid": "0000-0002-6018-6447"
    },
    {
      "affs": [
        38,
        39
      ],
      "name": "M. Arca Sedda"
    },
    {
      "name": "J. S. Areeda",
      "orcid": "0000-0003-0266-7936"
    },
    {
      "affs": [
        1
      ],
      "name": "N. Aritomi"
    },
    {
      "affs": [
        2,
        25
      ],
      "name": "F. Armato",
      "orcid": "0000-0002-8856-8877"
    },
    {
      "name": "Sharon Armstrong",
      "orcid": "0009-0009-4285-2360"
    },
    {
      "name": "N. Arnaud",
      "orcid": "0000-0001-6589-8673"
    },
    {
      "name": "M. Arogeti",
      "orcid": "0000-0001-5124-3350"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/fd42xrjcbch43.bib",
  "cited_by": 33,
  "doi": "10.1103/dlfv-z6m2",
  "fulltext_url": null,
  "id": "fd42xrjcbch43",
  "issns": [
    "2160-3308"
  ],
  "landing_url": "https://doi.org/10.1103/dlfv-z6m2",
  "language": "en",
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
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      "openalex",
      "3103|Pulsars and Gravitational Waves Research"
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  "openalex": "W4415910184",
  "pdf_url": null,
  "pmcid": null,
  "pmid": null,
  "published": "2026-07-21",
  "publisher": "American Physical Society",
  "ris": "https://research.draconitic.com/paper/fd42xrjcbch43.ris",
  "sources": [
    {
      "first_seen": "2026-11-07T13:20:44Z",
      "native_id": "W4415910184",
      "source": "openalex",
      "url": "https://doi.org/10.1103/dlfv-z6m2"
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  "subjects": [
    {
      "field": "astronomy",
      "origin": "openalex:3103|Pulsars and Gravitational Waves Research",
      "subfield": "high-energy-astrophysics"
    }
  ],
  "title": "Cosmological and High-Energy Physics Implications from Gravitational-Wave Background Searches in LIGO-Virgo-KAGRA’s O1–O4a Runs",
  "title_text": "Cosmological and High-Energy Physics Implications from Gravitational-Wave Background Searches in LIGO-Virgo-KAGRA’s O1–O4a Runs",
  "type": "peer-reviewed",
  "updated_at": "2026-11-08T13:20:37Z",
  "url": "https://research.draconitic.com/paper/fd42xrjcbch43",
  "venue": "Physical Review X",
  "versions": []
}