Search for Majorana Neutrinos Near the Inverted Mass Hierarchy Region with KamLAND-Zen
Search for Majorana Neutrinos Near the Inverted Mass Hierarchy Region with KamLAND-Zen
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DOI：
10.1103/physrevlett.117.082503
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发表时间：
2016-08-16
影响因子：
8.6
通讯作者：
Decowski, M. P.
中科院分区：
文献类型：
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作者：
Gando, A.;Gando, Y.;Decowski, M. P.
我们提出了一个改进的搜索无中微子双β（0 nu β β）衰变的136在KamLAND-Zen实验。由于氙负载的液体闪烁体的净化，我们实现了在以前的搜索中确定的Ag-110 m污染物的显着减少。结合第一阶段和第二阶段的结果，我们得到0 nu β β衰变半衰期的下限为T-1/2（0 nu）> 1.07 x 10（26）年（90% C.L.），比以前的限制提高了近六倍。使用普遍采用的核矩阵元计算，相应的上限的有效马约拉纳中微子质量的范围为61-165 meV。对于最乐观的核矩阵元，这个极限达到了准生中微子质量区的底部。
We present an improved search for neutrinoless double-beta (0 nu beta beta) decay of Xe-136 in the KamLAND-Zen experiment. Owing to purification of the xenon-loaded liquid scintillator, we achieved a significant reduction of the Ag-110m contaminant identified in previous searches. Combining the results from the first and second phase, we obtain a lower limit for the 0 nu beta beta decay half-life of T-1/2(0 nu) > 1.07 x 10(26) yr at 90% C.L., an almost sixfold improvement over previous limits. Using commonly adopted nuclear matrix element calculations, the corresponding upper limits on the effective Majorana neutrino mass are in the range 61-165 meV. For the most optimistic nuclear matrix elements, this limit reaches the bottom of the quasidegenerate neutrino mass region.