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First Indication of Terrestrial Matter Effects on Solar Neutrino Oscillation

2014; American Physical Society; Volume: 112; Issue: 9 Linguagem: Inglês

10.1103/physrevlett.112.091805

1092-0145

A. Renshaw, K. Abe, Y. Hayato, K. Iyogi, J. Kameda, Y. Kishimoto, M. Miura, S. Moriyama, M. Nakahata, Y. Nakano, S. Nakayama, H. Sekiya, M. Shiozawa, Y. Suzuki, A. Takeda, Y. Takenaga, T. Tomura, K. Ueno, T. Yokozawa, R. A. Wendell, T. J. Irvine, T. Kajita, K. Kaneyuki, K. P. Lee, Y. Nishimura, K. Okumura, T. C. Mclachlan, L. Labarga, S. Berkman, H. A. Tanaka, S. Tobayama, E. Kearns, J. L. Raaf, J. L. Stone, L. Sulak, M. Goldhabar, K. Bays, G. Carminati, W. R. Kropp, S. Mine, M. Smy, H. W. Sobel, K. S. Ganezer, J. Hill, W. E. Keig, Nguyễn Thị Hồng, J.Y. Kim, I. T. Lim, T. Akiri, A. Himmel, K. Scholberg, C. W. Walter, T. Wongjirad, T. Ishizuka, S. Tasaka, J. S. Jang, J. G. Learned, S. Matsuno, S. N. Smith, T. Hasegawa, Toru Ishida, T. Ishii, T. Kobayashi, T. Nakadaira, K. Nakamura, Y. Oyama, K. Sakashita, T. Sekiguchi, T. Tsukamoto, Y. Suzuki, Y. Takeuchi, C. Bronner, S. Hirota, K. Huang, K. Ieki, M. Ikeda, T. Kikawa, A. Minamino, T. Nakaya, Kenta Suzuki, Sentaro Takahashi, Y. Fukuda, K. Choi, Y. Itow, G. Mitsuka, P. Mijakowski, J. Hignight, J. Imber, C. K. Jung, C. Yanagisawa, H. Ishino, A. Kibayashi, Y. Koshio, T. Mori, M. Sakuda, T. Yano, Y. Kuno, R. Tacik, S. B. Kim, H. Okazawa, Y. Choi, K. Nishijima, M. Koshiba, Y. Totsuka, M. Yokoyama, K. Martens, Ll. Marti, M. R. Vagins, J. F. Martin, P. de Perio, A. Konaka, M. J. Wilking, S. Chen, Y. Zhang, R. J. Wilkes,

Dark Matter and Cosmic Phenomena

We report an indication that the elastic scattering rate of solar $^8$B neutrinos with electrons in the Super-Kamiokande detector is larger when the neutrinos pass through the Earth during nighttime. We determine the day/night asymmetry, defined as the difference of the average day rate and average night rate divided by the average of those two rates, to be $(-3.2\pm1.1(\text{stat})\pm0.5(\text{syst}))\%$, which deviates from zero by 2.7 $\sigma$. Since the elastic scattering process is mostly sensitive to electron-flavored solar neutrinos, a non-zero day/night asymmetry implies that the flavor oscillations of solar neutrinos are affected by the presence of matter within the neutrinos' flight path. Super-Kamiokande's day/night asymmetry is consistent with neutrino oscillations for $4\times10^{-5}$eV$^2\leq\Delta m^2_{21}\leq7\times10^{-5}$eV$^2$ and large mixing values of $\theta_{12}$, at the $68\%$ C.L.