We present results from the KamLAND-Zen double-beta decay experiment based on an exposure of 77.6 days with 129 kg of $^{136}$Xe. The measured two-neutrino double-beta decay half-life of $^{136}$Xe is $T_{1/2}^{2ν} = 2.38 \pm 0.02(stat) \pm 0.14(syst) \times 10^{21}$ yr, consistent with a recent measurement by EXO-200. We also obtain a lower limit for the neutrinoless double-beta decay half-life, $T_{1/2}^{0ν} > 5.7 \times 10^{24}$ yr at 90% confidence level (C.L.), which corresponds to almost a five-fold improvement over previous limits.
Limit on Neutrinoless ββ Decay of Xe-136 from the First Phase of KamLAND-Zen and Comparison with the Positive Claim in Ge-76
我们目前的结果，从第一阶段的KamLAND-Zen双β衰变实验，相当于89.5公斤/年的曝光量的氚-136。我们得到了无中微子双β衰变半衰期的下限为T_{1/2} ^{0ν} > 1.9 × 10^{25}年（90% C. L.）。KamLAND-Zen和EXO-200的综合结果给出T_{1/2} ^{0ν} > 3.4 x 10^{25}年（90% C. L.），其对应于< m_{ββ} >基于可用矩阵元计算的代表性范围的<（120-250）meV的马约拉纳中微子质量极限。使用这些计算，这一结果排除了马约拉纳中微子质量范围，该范围是从Ge-76中的无中微子双β衰变检测声明中预期的，由海德堡-莫斯科合作组织的一部分报告，超过97.5% C. L。
KamLAND-Zen报告了在净化氙装载液体闪烁体后，基于114.8活天，用^{136}氙对无中微子双β衰变进行的初步研究。在该数据中，在先前搜索中识别的有问题的^{110 m}Ag背景峰减少了10倍以上。通过结合KamLAND-Zen纯化前和纯化后的数据，我们获得了T_{1/2} ^{0ν} > 2.6 x 10^{25}年（90% C. L.）的0νββ衰变半衰期的初步下限。在纯化之后，将使用额外的低背景数据来增强搜索灵敏度。展望未来KamLAND-Zen升级的进一步改进。
Search for Majorana Neutrinos with the Complete KamLAND-Zen Dataset
Kamioka Observatory, Institute for Cosmic-Ray Research, The University of Tokyo（宇宙线研究所神冈观测室，东京大学）；Research Center for Neutrino Science, Tohoku University（东北大学中微子科学研究中心）；Department of Human Science, Obihiro University of Agriculture and Veterinary Medicine（带广畜产大学人类科学系）
Search for double-beta decay of 136Xe to excited states of 136Ba with the KamLAND-Zen experiment
A search for double- beta decays of 136Xe to excited states of 136Ba has been performed with the first phase data set of the KamLAND-Zen experiment. The 0+1, 2+1 and 2+2 transitions of 0ν\{beta}\{beta} decay were evaluated in an exposure of 89.5kg-yr of 136Xe, while the same transitions of 2ν\{beta}\{beta} decay were evaluated in an exposure of 61.8kg-yr. No excess over background was found for all decay modes. The lower half-life limits of the 2+1 state transitions of 0ν\{beta}\{beta} and 2ν\{beta}\{beta} decay were improved to T(0ν, 0+ \rightarrow 2+) > 2.6 \times 10^25 yr and T(2ν, 0+ \righ…
Probing $0νββ$ and $μ\to eγ$ via Fully Determined Dirac Mass Terms in LRSM with Double Seesaw
Indian Institute of Technology Bhilai（印度技术学院比莱分校）；Indian Institute of Technology Bombay（印度技术学院孟买分校）；Saha Institute of Nuclear Physics（萨哈核物理研究所）；Institute of Physics, Bhubaneswar（布巴内斯瓦尔物理研究所）
