Year: 2026
Type: preprint
Abstract: In 2020, Super-Kamiokande entered the SK-Gd phase, improving its sensitivity to low-energy electron antineutrinos through the detection of neutrons captured on gadolinium dissolved in the detector water. An analysis of reactor electron antineutrino data has been carried out using data from SK-Gd, with a total exposure of 411.52 live days. The observed prompt energy spectra and monthly event rates are consistent with the oscillated reactor antineutrino prediction after accounting for accidental, geoneutrino, and spallation backgrounds. The no-reactor hypothesis is disfavored with a reactor-antineutrino signal significance of approximately $6σ$. The oscillation parameters are measured to be $\sin^2θ_{12} = 0.500\pm0.155$ and $Δm^2_{21} = (9.08_{-0.54}^{+0.55}) \times 10^{-5} \mathrm{eV}^2$. A comparison with Super-Kamiokande solar neutrino measurements shows a statistical compatibility between the two datasets at the $1.9σ$ level. A combined solar and reactor fit in Super-Kamiokande yields best-fit values of $\sin^2θ_{12} = 0.332_{-0.026}^{+0.028}$ and $Δm^2_{21} = (8.94_{-0.47}^{+0.46}) \times 10^{-5} \mathrm{eV}^2$.
Source: arXiv (Cornell University)
Authors: Abe, K., Asaoka, Y., Harada, M., Hayato, Y., Hiraide, K., Hung, T. H., Ieki, K., Ikeda, M., Kameda, J., Kataoka, Y., Mine, S., Miura, M., Moriyama, S., Nakagiri, K., Nakahata, M., Nakayama, S., Noguchi, Y., Pronost, G., Sato, K., Sekiya, H., Shinoda, R., Shiozawa, M., Suzuki, Y., Takeda, A., Takemoto, Y., Tanaka, H., Chen, S., Itow, Y., Kajita, T., Nishijima, R., Okumura, K., Tashiro, T., Tomiya, T., Wang, X., Arcones, F. J. de Garay, Fernandez, P., Labarga, L., Samudio, D., Yanagisawa, C., Jargowsky, B., Kearns, E., Mirabito, J., Wan, L., Wester, T., Pointon, B. W., Bian, J., Cortez, B., Griskevich, N. J., Jiang, Y., Smy, M. B., Sobel, H. W., Takhistov, V., Hill, J., Xu, B. D., Jung, D., Moon, D. H., Park, R. G., Yang, B. S., Scholberg, K., Walter, C. W., Drapier, O., Ershova, A., Ferey, M., Hu, Z., Blévec, E. Le, Leplumey, L., Mueller, Th. A., Paganini, P., Quach, C., Rogly, R., Nakamura, T., Jang, J. S., Litchfield, R. P., Machado, L. N., Soler, F. J. P., Learned, J. G., Choi, K., Cao, S., Ngoc, T. V., Anthony, L. H. V., Prouse, N. W., Scott, M., Uchida, Y., Berardi, V., Calabria, N. F., Catanesi, M. G., Ospina, N., Radicioni, E., Langella, A., De Rosa, G., Burton, G. T., Collazuol, G., Feltre, M., Mattiazzi, M., Ludovici, L., Gonin, M., Périssé, L., Quilain, B., Fukazawa, M., Horiuchi, S., Kawabata, A., Liu, Y. M., Maekawa, Y., Nishimura, Y., Oka, A., Tanigawa, H., Utagawa, Z., Akutsu, R., Friend, M., Hasegawa, T., Hino, Y., Ishida, T., Kobayashi, T., Matsubara, T., Nakadaira, T., Oyama, Y., Yrey, A. Portocarrero, Sakashita, K., Sekiguchi, T., Bhuiyan, N., Di Lodovico, F., Katori, T., Kralik, R., Latham, N., Ramsden, R. M., Siccardi, V., Aoyama, S., Bambara, H., Inaba, Y., Ito, H., Nishigami, M., Sone, T., Suzuki, A. T., Takeuchi, Y., Wada, S., Zhong, H., Feng, J., Feng, L., Fujimoto, N., Han, S., Hikida, J., Kawaue, M., Kikawa, T., Nakanishi, F., Nakaya, T., Wendell, R. A., Jenkins, S. J., Limbu, U., McCauley, N., Fan, M., Wilking, M. J., Xie, Z., Fukuda, Y., Menjo, H., Yoshioka, Y., Lagoda, J., Zalipska, J., Yano, T., Mori, M., Jiang, J., Asano, Y., Hamaguchi, K., Ishino, H., Koshio, Y., Ohshita, S., Tada, T., Ishizuka, T., Barr, G., Barrow, D., Wark, D., Holin, A., Nova, F., Jo, M., Jung, S., Yoo, J., Kneale, L., Peacock, T., Stowell, P., Okazawa, H., Lakshmi, S. M., Hong, S., Kwon, E., Lee, M. W., Seo, J. W., Yu, I., Ashida, Y., Ichikawa, A. K., Kobayashi, S., Nakamura, K. D., Abe, S., Cai, W., Endo, Y., Goto, S., Kodama, S., Kong, Y., Hayasaki, H., Masaki, Y., Mizuno, Y., Muro, T., Nakagiri, K., Nakajima, Y., Sekiyama, M., Taniuchi, N., Yamazumi, T., Yokoyama, M., de Perio, P., Fujita, S., Jesús-Valls, C., Martens, K., Marti, Ll., Santos, A. D., Tsui, K. M., Vagins, M. R., Izumiyama, S., Kuze, M., Matsumoto, R., Ise, C., Ishitsuka, M., Sugo, M., Wako, M., Yamauchi, K., Nakano, Y., Yankelevich, A., Cormier, F., Gaur, R., Hartz, M., Konaka, A., Li, X., Smithers, B. R., Chen, S., Wu, Y., Zhang, A. Q., Zhang, B., Adhikary, H., Girgus, M., Govindaraj, P., Posiadala-Zezula, M., Prabhu, Y. S., Boyd, S. B., Edwards, R., Hadley, D., O'Flaherty, M., Richards, B., Ali, A., Jamieson, B., Bronner, C., Horiguchi, D., Minamino, A., Sasaki, Y.
Language: English
Topic: Neutrino Physics Research
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: U.S. Department of Energy, European Commission, Ministry of Education, Culture, Sports, Science and Technology, National Natural Science Foundation of China, National Research Foundation of Korea, Institute for Basic Science, Alliance de recherche numérique du Canada, Horizon 2020 Framework Programme, HORIZON EUROPE Framework Programme, Natural Sciences and Engineering Research Council of Canada, Science and Technology Facilities Council, Japan Society for the Promotion of Science, Nuclear Physics, NextGenerationEU
Awards: G1626428022, G1820956982, G187717830, G2814198339, G2818282093, G2907963052, G3049196905, G3297240425, G3345895242, G3477743816, G3634461281, G3831296399, G3837556332, G4313378819, G4352636101, G4919363105, G507055683, G5093298782, From Super-Kamiokande to Hyper-Kamiokande, G5719138819, G5925907655, G6810656081, G753483755, G7865097842, G8367957132, G8611458396
OpenAlex ID: W7220391337