Department of Physics and Astronomy, University of California, Irvine, Irvine, California 92697-4575, USA.
Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Gifu 506-1205, Japan.
Phys Rev Lett. 2015 Sep 18;115(12):121803. doi: 10.1103/PhysRevLett.115.121803.
Search results for nucleon decays p→e^{+}X, p→μ^{+}X, n→νγ (where X is an invisible, massless particle) as well as dinucleon decays np→e^{+}ν, np→μ^{+}ν, and np→τ^{+}ν in the Super-Kamiokande experiment are presented. Using single-ring data from an exposure of 273.4 kton·yr, a search for these decays yields a result consistent with no signal. Accordingly, lower limits on the partial lifetimes of τ_{p→e^{+}X}>7.9×10^{32} yr, τ_{p→μ^{+}X}>4.1×10^{32} yr, τ_{n→νγ}>5.5×10^{32} yr, τ_{np→e^{+}ν}>2.6×10^{32} yr, τ_{np→μ^{+}ν}>2.2×10^{32} yr, and τ_{np→τ^{+}ν}>2.9×10^{31} yr at a 90% confidence level are obtained. Some of these searches are novel.
在 Super-Kamiokande 实验中，对核子（p）→正电子（e^{+}）X、p→μ^{+}X、n→νγ（其中 X 是一个不可见的无质量粒子）以及双核子（np）→正电子（e^{+}）ν、np→μ^{+}ν、np→τ^{+}ν 的衰变进行了搜索。利用来自 273.4kton·yr 曝光量的单环数据，对这些衰变的搜索结果与没有信号一致。因此，τ_{p→e^{+}X}的部分寿命下限为>7.9×10^{32}yr、τ_{p→μ^{+}X}>4.1×10^{32}yr、τ_{n→νγ}>5.5×10^{32}yr、τ_{np→e^{+}ν}>2.6×10^{32}yr、τ_{np→μ^{+}ν}>2.2×10^{32}yr 和 τ_{np→τ^{+}ν}>2.9×10^{31}yr，置信水平为 90%。其中一些搜索是新颖的。
