无中微子双贝塔衰变：寻找马约拉纳中微子之路

无中微子双贝塔衰变是目前粒子物理与核物理学家积极寻找的一种极其稀有的原子核衰变模式。它的发现将验证中微子是否是其本身的反粒子，也就是通常指的马约拉纳费米子。同时这一物理过程破坏轻子数守恒，也可以为宇宙初期的正反物质不对称性提供重要的条件。鉴于其极重要的物理意义，国际上多个实验组利用不同的探测器技术，在多种不同的目标同位素中寻找这一突破粒子物理标准模型的稀有衰变。目前主流实验还未发现确定的无中微子双贝塔衰变信号，但对其半衰期的限制已经达到了10²⁶年量级。国内近期也开展了一系列预研实验，期望在未来几年内可以确定一到两个切实可行的实验方案，开展吨级实验。

Neutrinoless double beta decay: searching for Majorana neutrinos

The search for neutrino-less double beta decay (NLDBD), an extremely rare decay process of certain nuclei, is being actively pursued by particle and nuclear physicists. A discovery would confirm that neutrinos are their own anti-particle, i.e. Majorana fermions. This decay also violates the conservation of lepton number and provides a viable explanation for the matter-antimatter asymmetry of the early universe. Around the world, many collaborations utilize different detector techniques to search for this rare process beyond the Standard Model of particle physics in different isotopes. No positive signals have been identified so far and the half-life limit of NLDBD has been set to at least 10²⁶ years. Recently a series of R&D projects have started in China, which hopefully will evolve to one or two future ton scale NLDBD experiments in the near future.