Probing scalar-neutrino and scalar-dark-matter interactions with PandaX-4T
PandaX Collaboration, Tao Li, Zihao Bo, Wei Chen, Xun Chen, Yunhua Chen, Chen Cheng, Xiangyi Cui, Manna Deng, Yingjie Fan, Deqing Fang, Xuanye Fu, Zhixing Gao, Yujie Ge, Lisheng Geng, Karl Giboni, Xunan Guo, Xuyuan Guo, Zichao Guo, Chencheng Han, Ke Han, Changda He, Jinrong He, Houqi Huang, Junting Huang, Yule Huang, Ruquan Hou, Xiangdong Ji, Yonglin Ju, Xiaorun Lan, Chenxiang Li, Jiafu Li, Mingchuan Li, Peiyuan Li, Shuaijie Li, Tao Li, Yangdong Li, Zhiyuan Li, Qing Lin, Jianglai Liu, Yuanchun Liu, Congcong Lu, Xiaoying Lu, Lingyin Luo, Yunyang Luo, Yugang Ma, Yajun Mao, Yue Meng, Binyu Pang, Ningchun Qi, Zhicheng Qian, Xiangxiang Ren, Dong Shan, Xiaofeng Shang, Xiyuan Shao, Guofang Shen, Manbin Shen, Wenliang Sun, Xuyan Sun, Yi Tao, Yueqiang Tian, Yuxin Tian, Anqing Wang, Guanbo Wang, Hao Wang, Haoyu Wang, Jiamin Wang, Lei Wang, Meng Wang, Qiuhong Wang, Shaobo Wang, Shibo Wang, Siguang Wang, Wei Wang, Xu Wang, Zhou Wang, Yuehuan Wei, Weihao Wu, Yuan Wu, Mengjiao Xiao, Xiang Xiao, Yuhan Xie, Kaizhi Xiong, Jianqin Xu, Yifan Xu, Shunyu Yao, Binbin Yan, Xiyu Yan, Yong Yang, Peihua Ye, Chunxu Yu, Ying Yuan, Zhe Yuan, Youhui Yun, Xinning Zeng, Minzhen Zhang, Peng Zhang, Shibo Zhang, Siyuan Zhang, Shu Zhang, Tao Zhang, Wei Zhang, Yang Zhang, Yingxin Zhang, Yuanyuan Zhang, Li Zhao, Kangkang Zhao, Jifang Zhou, Jiaxu Zhou, Jiayi Zhou, Ning Zhou, Xiaopeng Zhou, Zhizhen Zhou, Chenhui Zhu, Yihong Zhong, Van Que Tran, Michael J. Ramsey-Musolf
TL;DR
The work tests the hypothesis that a light scalar mediator $\phi$ couples neutrinos and dark matter, with potential implications for the Hubble tension and small-scale structure. It carries out a direct spectral search for $\nu$-scalar interactions using $^{136}$Xe double β decay data from PandaX-4T, fitting the spectrum across mediator masses $m_{\phi}$ from 10 keV to 2390 keV and the massless case, and translating limits to $g_{\nu\phi}$ via $\Gamma_{\beta\beta\phi}=(g_{\nu\phi})^2 |M_{\nu\phi}|^2 {\cal G}_{\nu\phi}$ with $|M_{\nu\phi}| \approx |M_{0\nu}|$ and ${\cal G}_{\nu\phi}$ defined in the phase-space factor. The analysis yields the most stringent laboratory constraints on $g_{\nu\phi}$ for $m_\phi \lesssim 2$ MeV, disfavoring moderately and strongly interacting models that aim to resolve the Hubble tension, and it discusses complementary BBN bounds for $m_\phi \lesssim 1.3$ MeV. Assuming the same scalar mediates dark matter self-interactions, the study combines these bounds with cosmological limits on DM–neutrino scattering to constrain $g_{\chi\phi}$ and shows tension with SIDM parameter space unless $g_{\nu\phi}$ is reduced or cosmological constraints are relaxed. Overall, the work demonstrates that double β decay data offer a powerful laboratory probe of neutrino and dark matter portals and that PandaX-4T can test beyond-the-Standard-Model scenarios involving light scalar mediators.
Abstract
Scalar-mediated interactions may exist among neutrinos, dark matter particles, or between the two. Double $β$-decay experiments provide a powerful tool to probe such exotic interactions. Using $^{136}$Xe double $β$-decay data from PandaX-4T, we perform the first direct spectral search in the energy range of 20 to 2800~keV, setting the most stringent limits to date on scalar-mediated neutrino self-interactions for mediator masses below 2~MeV$/c^2$. These results place significant constraints on models invoking such interactions to alleviate the Hubble Tension. Assuming the same scalar also mediates dark matter self-interactions, constraints on the dark matter-scalar interactions can be placed in conjunction with cosmological constraints.