{
  "abstract": "We report a search for the diffuse supernova neutrino background (DSNB) with the KamLAND detector, targeting electron antineutrinos ( ν ¯ e ) via inverse beta decay in the neutrino energy range of 8.3–30.8 MeV. Using an exposure of 9.02 kton-yr (8.3–9.3 MeV) and 9.42 kton-yr (9.3–30.8 MeV) with a liquid scintillator, we observe seven candidate events after applying a new deep-neural-network-based event classification technique. This is consistent with the background-only expectation of 16.2 ± 9.4 events, which includes systematic uncertainties associated with the neural-network selection. A spectral analysis of the energy and radial distributions finds no significant excess attributable to the DSNB. We therefore set 90% confidence-level upper limits on the DSNB flux of 38–43 cm ⁻² s ⁻¹ , depending on the assumed DSNB model. We also derive model-independent 90% confidence-level upper limits on the ν ¯ e flux, which are among the most stringent constraints below 13.3 MeV. Beyond the DSNB search itself, this work establishes neural-network-based event classification as a promising approach for suppressing neutron-associated backgrounds in liquid-scintillator neutrino detectors. The improved sensitivity also enables an astrophysical interpretation of the average neutrino emission from core-collapse supernovae and highlights the complementary role of low-threshold liquid-scintillator detectors in future DSNB searches.",
  "abstract_shown": true,
  "affiliations": [
    "Tohoku University",
    "Obihiro University of Agriculture and Veterinary Medicine",
    "The University of Tokyo",
    "Osaka University",
    "Tokushima University",
    "Nagoya University",
    "Tokyo University of Science",
    "Lawrence Berkeley National Laboratory",
    "University of Hawai'i at Manoa",
    "Massachusetts Institute of Technology",
    "University of Tennessee",
    "Triangle Universities Nuclear Laboratory",
    "Physics Department at Duke University",
    "North Carolina Central University",
    "The University of North Carolina at Chapel Hill",
    "Virginia Polytechnic Institute and State University"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 74,
  "authors": [
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        0
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      "name": "D. Chernyak",
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        0
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      "name": "T. Eda"
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    {
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        0
      ],
      "name": "M. Eizuka",
      "orcid": "0000-0002-1043-3438"
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    {
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        0
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      "name": "R. Endo"
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        0,
        1
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      "name": "A. Gando",
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        0,
        1
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      "name": "Y. Gando"
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        0
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      "name": "T. Hachiya",
      "orcid": "0000-0002-4238-7990"
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      "name": "F. Haneishi"
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      "name": "K. Hata",
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      "name": "T. Hirai"
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      "name": "K. Hosokawa",
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      "name": "K. Ichimura",
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      "name": "H. Ikeda"
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      "name": "K. Inoue"
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      "name": "K. Ishidoshiro",
      "orcid": "0000-0001-9271-2301"
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      "name": "Y. Kamei",
      "orcid": "0000-0002-6265-1197"
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      ],
      "name": "N. Kawada",
      "orcid": "0000-0003-2350-2786"
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    {
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        0
      ],
      "name": "Y. Kishimoto"
    },
    {
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        0,
        2
      ],
      "name": "M. Koga"
    },
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        0
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      "name": "K. Mikami"
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        0
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      "name": "H. Miyake",
      "orcid": "0009-0001-4510-0641"
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    {
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      "name": "K. Mizukoshi"
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      "name": "D. Morita",
      "orcid": "0009-0002-6277-4047"
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      "name": "K. Nakamura"
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      "name": "R. Nakamura"
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        0
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      "name": "J. Nakane"
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    {
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        0
      ],
      "name": "Y. Nakano"
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    {
      "affs": [
        0
      ],
      "name": "N. Obata"
    },
    {
      "affs": [
        0
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      "name": "Y. Ota"
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    {
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        0
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      "name": "K. Saito",
      "orcid": "0009-0008-8794-283X"
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    {
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      ],
      "name": "I. Sakaki"
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    {
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        0
      ],
      "name": "I. Shimizu",
      "orcid": "0000-0003-2705-6461"
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    {
      "affs": [
        0
      ],
      "name": "J. Shirai"
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    {
      "affs": [
        0
      ],
      "name": "A. Suzuki"
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    {
      "affs": [
        0
      ],
      "name": "K. Tachibana"
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    {
      "affs": [
        0
      ],
      "name": "A. Takeuchi"
    },
    {
      "affs": [
        0
      ],
      "name": "K. Tamae"
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    {
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        0
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      "name": "H. Watanabe",
      "orcid": "0000-0002-2363-5637"
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      "name": "Z. Xu",
      "orcid": "0009-0008-6580-0259"
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    {
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        3
      ],
      "name": "S. Yoshida",
      "orcid": "0000-0002-6970-9021"
    },
    {
      "affs": [
        3
      ],
      "name": "S. Umehara"
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    {
      "affs": [
        4
      ],
      "name": "K. Fushimi",
      "orcid": "0000-0001-5107-6724"
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    {
      "affs": [
        4
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      "name": "K. Kotera"
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    {
      "affs": [
        4
      ],
      "name": "Y. Urano"
    },
    {
      "affs": [
        5
      ],
      "name": "S. Kurosawa"
    },
    {
      "affs": [
        6
      ],
      "name": "H. Ozaki",
      "orcid": "0000-0003-3682-432X"
    },
    {
      "affs": [
        7
      ],
      "name": "B.E. Berger"
    },
    {
      "affs": [
        2,
        7
      ],
      "name": "B.K. Fujikawa",
      "orcid": "0000-0002-7001-717X"
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    {
      "affs": [
        8
      ],
      "name": "J.G. Learned"
    },
    {
      "affs": [
        8
      ],
      "name": "J. Maricic"
    },
    {
      "affs": [
        8
      ],
      "name": "Z. Li"
    },
    {
      "affs": [
        9
      ],
      "name": "Z. Fu"
    },
    {
      "affs": [
        9
      ],
      "name": "S. Ghosh"
    },
    {
      "affs": [
        9
      ],
      "name": "J. Smolsky",
      "orcid": "0000-0002-1916-4182"
    },
    {
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        9
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      "name": "L.A. Winslow"
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    {
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        10
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      "name": "Y. Efremenko",
      "orcid": "0000-0002-5132-3112"
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    {
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        11,
        12,
        13,
        14
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      "name": "H.J. Karwowski",
      "orcid": "0000-0003-0734-655X"
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    {
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        12,
        13,
        14
      ],
      "name": "D.M. Markoff",
      "orcid": "0000-0002-2313-5763"
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        11,
        12,
        13,
        14
      ],
      "name": "W. Tornow",
      "orcid": "0000-0003-4031-6926"
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        15
      ],
      "name": "S. Dell’Oro"
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  "doi": "10.3847/1538-4357/aeb2ea",
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    "1538-4357",
    "0004-637X"
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  "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/",
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  "pdf_url": "https://iopscience.iop.org/article/10.3847/1538-4357/aeb2ea/pdf",
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  "published": "2026-11-05",
  "publisher": "American Astronomical Society",
  "ris": "https://research.draconitic.com/paper/dp6qcpnm93ty5.ris",
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  "subjects": [
    {
      "field": "astronomy",
      "origin": "journal-openalex:3103|Stellar, planetary, and galactic studies",
      "subfield": "stellar"
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  ],
  "title": "Search for Diffuse Supernova Neutrino Background in the Full KamLAND Dataset with Neural-network-based Event Classification",
  "title_text": "Search for Diffuse Supernova Neutrino Background in the Full KamLAND Dataset with Neural-network-based Event Classification",
  "type": "peer-reviewed",
  "updated_at": "2026-11-07T00:20:58Z",
  "url": "https://research.draconitic.com/paper/dp6qcpnm93ty5",
  "venue": "The Astrophysical Journal",
  "versions": []
}