collaboration, S-K; Abe, K; Hayato, Y; Iida, T; Ishihara, K; Kameda, J; Koshio, Y; Minamino, A; Mitsuda, C; Miura, M; Moriyama, S; Nakahata, M; Obayashi, Y; Ogawa, H; Sekiya, H; Shiozawa, M; Suzuki, Y; Takeda, A; Takeuchi, Y; Ueshima, K; Watanabe, H; Higuchi, I; Ishihara, C; Ishitsuka, M; Kajita, T; Kaneyuki, K; Mitsuka, G; Nakayama, S; Nishino, H; Okumura, K; Saji, C; Takenaga, Y; Clark, S; Desai, S; Dufour, F; Herfurth, A; Kearns, E; Likhoded, S; Litos, M; Raaf, JL; Stone, JL; Sulak, LR et al., *Search for n-nbar oscillation in Super-Kamiokande*,
Phys. Rev. D, vol. 91 no. 7
(April, 2015),
pp. 072006 [doi] .
**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.*