论文标题
搜索$π^0 $衰减到隐形粒子
Search for $π^0$ decays to invisible particles
论文作者
论文摘要
CERN SPS的NA62实验报告了一项针对$ 4 \ times10^{9} $标记的样品的研究$π^0 $ erson，从$ k^+ \toπ^+π^0（γ）$，搜索$π^0 $ to to Invisible粒子的衰减。未观察到超过预期的背景波动的信号。上限的上限为$ 4.4 \ times10^{ - 9} $的分支比率设置为90％的置信度，以前的结果提高了60倍。也可以将此结果解释为与模型无关的上限，该衰减的分支比率$ k^+ \ to phot $ k^+ \toπ^+ x $ a $ x $ a $ x $ a $ x $ 1. GEV $/c^2 $和大于100 ps的休息寿命。假设$ x $是轴突状的粒子，具有占主导地位的fermion耦合或与标准模型Higgs玻色子混合，则获得了模型依赖性上限。
The NA62 experiment at the CERN SPS reports a study of a sample of $4 \times10^{9}$ tagged $π^0$ mesons from $K^+ \to π^+ π^0 (γ)$, searching for the decay of the $π^0$ to invisible particles. No signal is observed in excess of the expected background fluctuations. An upper limit of $4.4 \times10^{-9}$ is set on the branching ratio at 90% confidence level, improving on previous results by a factor of 60. This result can also be interpreted as a model-independent upper limit on the branching ratio for the decay $K^+ \to π^+ X$, where $X$ is a particle escaping detection with mass in the range 0.110-0.155 GeV$/c^2$ and rest lifetime greater than 100 ps. Model-dependent upper limits are obtained assuming $X$ to be an axion-like particle with dominant fermion couplings or a dark scalar mixing with the Standard Model Higgs boson.
