Searching for Two-Neutrino and Neutrinoless Double Beta Decay of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>Xe</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>134</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:math> with the PandaX-4T Experiment
Xiyu Yan, Zhaokan Cheng, Abdusalam Abdukerim, Zihao Bo, Wei Chen, Xun Chen, Chen Cheng, Xiangyi Cui, Yingjie Fan, Deqing Fang, Changbo Fu, Mengting Fu, Li‐Sheng Geng, Karl Giboni, Linhui Gu, Xuyuan Guo, Chencheng Han, K. Han, Changda He, Jinrong He, Di Huang, Yanlin Huang, J. Huang, Zhou Huang, Ruquan Hou, Yu Hou, Xiangdong Ji, Yonglin Ju, Chenxiang Li, Jiafu Li, Mingchuan Li, Shuaijie Li, Tao Li, Q. Lin, Jianglai Liu, Xiaoying Lu, Congcong Lu, Lingyin Luo, Yunyang Luo, Wenbo Ma, Y. G., Yajun Mao, Yue Meng, Xuyang Ning, Binyu Pang, Ningchun Qi, Zhicheng Qian, Xiangxiang Ren, Nasir Shaheed, Xiaofeng Shang, Xiyuan Shao, Guofang Shen, Lin Si, Wenliang Sun, Andi Tan, Yi Tao, Anqing Wang, Meng Wang, Qiuhong Wang, Shaobo Wang, Siguang Wang, Wei Wang, Xiuli Wang, Zhou Wang, Yuehuan Wei, Mengmeng Wu, Weihao Wu, Jingkai Xia, Mengjiao Xiao, Xiang Xiao, Pengwei Xie, Binbin Yan, Jijun Yang, Yong Yang, Yukun Yao, Chunxu Yu, Ying Yuan, Zhe Yuan, Xinning Zeng, Dan Zhang, Minzhen Zhang, Peng Zhang, Shibo Zhang, Shu Zhang, Tao Zhang, Wei Zhang, Yang Zhang, Yingxin Zhang, Yuanyuan Zhang, Li Zhao, Qibin Zheng, Jifang Zhou, Ning Zhou, Xiaopeng Zhou, Yong Zhou, Yubo Zhou
Abstract
$^{134}\mathrm{Xe}$ is a candidate isotope for neutrinoless double beta decay ($0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$) search. In addition, the two-neutrino case ($2\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$) allowed by the standard model of particle physics has not yet been observed. With the 656-kg natural xenon in the fiducial volume of the PandaX-4T detector, which contains 10.4% of $^{134}\mathrm{Xe}$, and its initial 94.9-day exposure, we have established the most stringent constraints on $2\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ and $0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ of $^{134}\mathrm{Xe}$ half-lives, with limits of $2.8\ifmmode\times\else\texttimes\fi{}{10}^{22}\text{ }\text{ }\mathrm{yr}$ and $3.0\ifmmode\times\else\texttimes\fi{}{10}^{23}\text{ }\text{ }\mathrm{yr}$ at 90% confidence level, respectively. The $2\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ ($0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$) limit surpasses the previously reported best result by a factor of 32 (2.7), highlighting the potential of large monolithic natural xenon detectors for double beta decay searches.