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arXiv · 1109.4227

Search for n-nbar oscillation in Super-Kamiokande

Kamiokande collaboration·K. Abe·Y. Hayato·T. Iida·K. Ishihara·J. Kameda·Y. Koshio·A. Minamino·C. Mitsuda·M. Miura·S. Moriyama·M. Nakahata·Y. Obayashi·H. Ogawa·H. Sekiya·M. Shiozawa·Y. Suzuki·A. Takeda·Y. Takeuchi·K. Ueshima·H. Watanabe·I. Higuchi·C. Ishihara·M. Ishitsuka·T. Kajita·K. Kaneyuki·G. Mitsuka·S. Nakayama·H. Nishino·K. Okumura·C. Saji·Y. Takenaga·S. Clark·S. Desai·F. Dufour·A. Herfurth·E. Kearns·S. Likhoded·M. Litos·J. L. Raaf·J. L. Stone·L. R. Sulak·W. Wang·M. Goldhaber·D. Casper·J. P. Cravens·J. Dunmore·J. Griskevich·W. R. Kropp·D. W. Liu·S. Mine·C. Regis·M. B. Smy·H. W. Sobel·M. R. Vagins·K. S. Ganezer·B. Hartfiel·J. Hill·W. E. Keig·J. S. Jang·I. S. Jeoung·J. Y. Kim·I. T. Lim·K. Scholberg·N. Tanimoto·C. W. Walter·R. Wendell·R. W. Ellsworth·S. Tasaka·G. Guillian·J. G. Learned·S. Matsuno·M. D. Messier·A. K. Ichikawa·T. Ishida·T. Ishii·T. Iwashita·T. Kobayashi·T. Nakadaira·K. Nakamura·K. Nishikawa·K. Nitta·Y. Oyama·A. T. Suzuki·M. Hasegawa·H. Maesaka·T. Nakaya·T. Sasaki·H. Sato·H. Tanaka·S. Yamamoto·M. Yokoyama·T. J. Haines·S. Dazeley·S. Hatakeyama·R. Svoboda·G. W. Sullivan·R. Gran·A. Habig·Y. Fukuda
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Abstract

A search for neutron-antineutron ($n-\bar{n}$) oscillation was undertaken in Super-Kamiokande using the 1489 live-day or $2.45 \times 10^{34}$ neutron-year exposure data. This process violates both baryon and baryon minus lepton numbers by an absolute value of two units and is predicted by a large class of hypothetical models where the seesaw mechanism is incorporated to explain the observed tiny neutrino masses and the matter-antimatter asymmetry in the Universe. No evidence for $n-\bar{n}$ oscillation was found, the lower limit of the lifetime for neutrons bound in ${}^{16}$O, in an analysis that included all of the significant sources of experimental uncertainties, was determined to be $1.9 \times 10^{32}$~years at the 90\% confidence level. The corresponding lower limit for the oscillation time of free neutrons was calculated to be $2.7 \times 10^8$~s using a theoretical value of the nuclear suppression factor of $0.517 \times 10^{23}$~s$^{-1}$ and its uncertainty.

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Kamiokande collaboration, K. Abe, Y. Hayato, T. Iida, K. Ishihara, J. Kameda, Y. Koshio, A. Minamino, C. Mitsuda, M. Miura, S. Moriyama, M. Nakahata, Y. Obayashi, H. Ogawa, H. Sekiya, M. Shiozawa, Y. Suzuki, A. Takeda, Y. Takeuchi, K. Ueshima, H. Watanabe, I. Higuchi, C. Ishihara, M. Ishitsuka, T. Kajita, K. Kaneyuki, G. Mitsuka, S. Nakayama, H. Nishino, K. Okumura, C. Saji, Y. Takenaga, S. Clark, S. Desai, F. Dufour, A. Herfurth, E. Kearns, S. Likhoded, M. Litos, J. L. Raaf, J. L. Stone, L. R. Sulak, W. Wang, M. Goldhaber, D. Casper, J. P. Cravens, J. Dunmore, J. Griskevich, W. R. Kropp, D. W. Liu, S. Mine, C. Regis, M. B. Smy, H. W. Sobel, M. R. Vagins, K. S. Ganezer, B. Hartfiel, J. Hill, W. E. Keig, J. S. Jang, I. S. Jeoung, J. Y. Kim, I. T. Lim, K. Scholberg, N. Tanimoto, C. W. Walter, R. Wendell, R. W. Ellsworth, S. Tasaka, G. Guillian, J. G. Learned, S. Matsuno, M. D. Messier, A. K. Ichikawa, T. Ishida, T. Ishii, T. Iwashita, T. Kobayashi, T. Nakadaira, K. Nakamura, K. Nishikawa, K. Nitta, Y. Oyama, A. T. Suzuki, M. Hasegawa, H. Maesaka, T. Nakaya, T. Sasaki, H. Sato, H. Tanaka, S. Yamamoto, M. Yokoyama, T. J. Haines, S. Dazeley, S. Hatakeyama, R. Svoboda, G. W. Sullivan, R. Gran, A. Habig, Y. Fukuda. 2011-09-20. Search for n-nbar oscillation in Super-Kamiokande. https://doi.org/10.1103/physrevd.91.072006

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