Precision Analysis of the 136Xe Two-Neutrino beta beta Spectrum in KamLAND-Zen and Its Impact on the Quenching of Nuclear Matrix Elements
Precision Analysis of the 136Xe Two-Neutrino beta beta Spectrum in KamLAND-Zen and Its Impact on the Quenching of Nuclear Matrix Elements
复制标题
KamLAND-Zen 中 136Xe 二中微子 β β 谱的精确分析及其对核基体元素猝灭的影响
DOI：
10.1103/physrevlett.122.192501
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发表时间：
2019
影响因子：
8.6
通讯作者：
A. Gando et al. (KamLAND-Zen Collaboration)
中科院分区：
文献类型：
--
作者：
小林研介;W. J. Munro;A. Gando et al. (KamLAND-Zen Collaboration)
本文根据KamLAND-Zen实验获得的高统计数据，对0.8MeV以上的双中微子电子能谱进行了精确的分析。改进的双中微子形式使我们能够测量主导和次主导核矩阵元素（NME）的比值。从核壳模型和大多数准粒子随机相近似（QRPA）计算的理论预测与实验极限是一致的。然而，在90%的置信水平下，目前的测量排除了QRPA允许的部分范围。我们的分析表明，预测值对NME的淬灭以及中间核中低能态和高能态的竞争贡献是敏感的。由于这些方面在无中微子衰变中也起作用，因此为可靠的无中微子NME提供了新的见解。
We present a precision analysis of thetwo-neutrinoelectron spectrum above 0.8 MeV, based on high-statistics data obtained with the KamLAND-Zen experiment. An improved formalism for the two-neutrinorate allows us to measure the ratio of the leading and subleadingnuclear matrix elements (NMEs),. Theoretical predictions from the nuclear shell model and the majority of the quasiparticle random-phase approximation (QRPA) calculations are consistent with the experimental limit. However, part of therange allowed by the QRPA is excluded by the present measurement at the 90% confidence level. Our analysis reveals that predictedvalues are sensitive to the quenching of NMEs and the competing contributions from low- and high-energy states in the intermediate nucleus. Because these aspects are also at play in neutrinolessdecay,provides new insights toward reliable neutrinolessNMEs.