The standard model of particle physics is remarkably successful because it is consistent with (almost) all experimental results. However, it fails to explain dark matter, dark energy and the imbalance between matter and antimatter in the Universe. Because discrepancies between standard-model predictions and experimental observations may provide evidence of new physics, an accurate evaluation of these predictions requires highly precise values of the fundamental physical constants. Among them, the fine-structure constant α is of particular importance because it sets the strength of the electromagnetic interaction between light and charged elementary particles, such as the electron and the muon. Here we use matter-wave interferometry to measure the recoil velocity of a rubidium atom that absorbs a photon, and determine the fine-structure constant α-1 = 137.035999206(11) with a relative accuracy of 81 parts per trillion. The accuracy of eleven digits in α leads to an electron g factor1,2-the most precise prediction of the standard model-that has a greatly reduced uncertainty. Our value of the fine-structure constant differs by more than 5 standard deviations from the best available result from caesium recoil measurements3. Our result modifies the constraints on possible candidate dark-matter particles proposed to explain the anomalous decays of excited states of 8Be nuclei4 and paves the way for testing the discrepancy observed in the magnetic moment anomaly of the muon5 in the electron sector6.

中文翻译：

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以 81 万亿分之一的精度确定精细结构常数

粒子物理学的标准模型非常成功，因为它与（几乎）所有实验结果一致。然而，它无法解释暗物质、暗能量以及宇宙中物质与反物质之间的不平衡。由于标准模型预测和实验观察之间的差异可能会提供新物理学的证据，因此对这些预测的准确评估需要基本物理常数的高度精确值。其中，精细结构常数 α 特别重要，因为它设定了光与带电基本粒子（如电子和 μ 子）之间电磁相互作用的强度。在这里，我们使用物质波干涉测量法来测量吸收光子的铷原子的反冲速度，并确定精细结构常数 α-1 = 137.035999206(11)，相对精度为万亿分之 81。α 中 11 位数字的准确性导致电子 g 因子 1,2 - 标准模型的最精确预测 - 其不确定性大大降低。我们的精细结构常数值与铯反冲测量的最佳可用结果相差超过 5 个标准偏差。我们的结果修改了对可能的候选暗物质粒子的约束，以解释 8Be 核激发态的异常衰变，并为测试在电子扇区中 μ 5 的磁矩异常中观察到的差异铺平了道路。2-标准模型的最精确预测-具有大大降低的不确定性。我们的精细结构常数值与铯反冲测量的最佳可用结果相差超过 5 个标准偏差。我们的结果修改了对可能的候选暗物质粒子的约束，以解释 8Be 核激发态的异常衰变，并为测试在电子扇区中 μ 5 的磁矩异常中观察到的差异铺平了道路。2-标准模型的最精确预测-具有大大降低的不确定性。我们的精细结构常数值与铯反冲测量的最佳可用结果相差超过 5 个标准偏差。我们的结果修改了对可能的候选暗物质粒子的约束，以解释 8Be 核激发态的异常衰变，并为测试在电子扇区中 μ 5 的磁矩异常中观察到的差异铺平了道路。