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arXiv · 2610.35619

Indication of Electron Antineutrinos from the Diffuse Supernova Neutrino Background

Kamiokande Collaboration·K. Abe·Y. Asaoka·M. Harada·Y. Hayato·K. Hiraide·T. H. Hung·K. Ieki·M. Ikeda·J. Kameda·Y. Kataoka·S. Mine·M. Miura·S. Moriyama·K. Nakagiri·M. Nakahata·S. Nakayama·Y. Noguchi·G. Pronost·K. Sato·H. Sekiya·R. Shinoda·M. Shiozawa·Y. Suzuki·A. Takeda·Y. Takemoto·H. Tanaka·S. Chen·Y. Itow·T. Kajita·R. Nishijima·K. Okumura·T. Tashiro·T. Tomiya·X. Wang·F. J. de Garay Arcones·P. Fernandez·L. Labarga·D. Samudio·C. Yanagisawa·B. Jargowsky·E. Kearns·J. Mirabito·L. Wan·T. Wester·B. W. Pointon·J. Bian·B. Cortez·N. J. Griskevich·Y. Jiang·M. B. Smy·H. W. Sobel·V. Takhistov·J. Hill·B. D. Xu·D. Jung·D. H. Moon·R. G. Park·B. S. Yang·K. Scholberg·C. W. Walter·A. Chahlaoui·O. Drapier·A. Ershova·M. Ferey·Z. Hu·E. Le Blévec·T. Leplumey·Th. A. Mueller·P. Paganini·C. Quach·R. Rogly·T. Nakamura·J. S. Jang·R. P. Litchfield·L. N. Machado·F. J. P. Soler·J. G. Learned·K. Choi·S. Cao·T. V. Ngoc·L. H. V. Anthony·N. W. Prouse·M. Scott·Y. Uchida·V. Berardi·N. F. Calabria·M. G. Catanesi·N. Ospina·E. Radicioni·A. Langella·G. De Rosa·G. T. Burton·G. Collazuol·M. Feltre·M. Mattiazzi·L. Ludovici·M. Gonin·L. Périssé·B. Quilain
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Abstract

We report an indication of $\barν_e$ from the diffuse supernova neutrino background (DSNB) based on a spectral fit analysis of a 5003.0-day dataset in Super-Kamiokande. Key improvements over previous searches include enhanced rejection of atmospheric $ν$ backgrounds, updated evaluations of systematic uncertainties, and a refined spectral fitting method. Using a representative DSNB model, the best-fit flux was determined to be $3.6^{+1.6}_{-1.5}~\mathrm{cm^{-2}\,s^{-1}}$ for $E_ν>13.3$~MeV, corresponding to a $2.6σ$ tension with a null hypothesis ($99.5\%$ C.L., one-sided). Similar significances were obtained with signal models of varying spectral shapes.

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Kamiokande Collaboration, K. Abe, Y. Asaoka, M. Harada, Y. Hayato, K. Hiraide, T. H. Hung, K. Ieki, M. Ikeda, J. Kameda, Y. Kataoka, S. Mine, M. Miura, S. Moriyama, K. Nakagiri, M. Nakahata, S. Nakayama, Y. Noguchi, G. Pronost, K. Sato, H. Sekiya, R. Shinoda, M. Shiozawa, Y. Suzuki, A. Takeda, Y. Takemoto, H. Tanaka, S. Chen, Y. Itow, T. Kajita, R. Nishijima, K. Okumura, T. Tashiro, T. Tomiya, X. Wang, F. J. de Garay Arcones, P. Fernandez, L. Labarga, D. Samudio, C. Yanagisawa, B. Jargowsky, E. Kearns, J. Mirabito, L. Wan, T. Wester, B. W. Pointon, J. Bian, B. Cortez, N. J. Griskevich, Y. Jiang, M. B. Smy, H. W. Sobel, V. Takhistov, J. Hill, B. D. Xu, D. Jung, D. H. Moon, R. G. Park, B. S. Yang, K. Scholberg, C. W. Walter, A. Chahlaoui, O. Drapier, A. Ershova, M. Ferey, Z. Hu, E. Le Blévec, T. Leplumey, Th. A. Mueller, P. Paganini, C. Quach, R. Rogly, T. Nakamura, J. S. Jang, R. P. Litchfield, L. N. Machado, F. J. P. Soler, J. G. Learned, K. Choi, S. Cao, T. V. Ngoc, L. H. V. Anthony, N. W. Prouse, M. Scott, Y. Uchida, V. Berardi, N. F. Calabria, M. G. Catanesi, N. Ospina, E. Radicioni, A. Langella, G. De Rosa, G. T. Burton, G. Collazuol, M. Feltre, M. Mattiazzi, L. Ludovici, M. Gonin, L. Périssé, B. Quilain. 2026-10-26. Indication of Electron Antineutrinos from the Diffuse Supernova Neutrino Background. https://arxiv.org/abs/2610.35619

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