Testing physics using the hydrogen atom Discrepancy between the proton radius determined from hydrogen and muonic hydrogen spectroscopy data, the so-called “proton radius puzzle,” has been a focus of the physics community for more than a decade now. Using two-photon ultraviolet frequency comb spectroscopy below 1 kilohertz, Grinin et al. report a high-precision measurement of the 1S-3S transition frequency in atomic hydrogen (see the Perspective by Ubachs). Combining this measurement with the data for the 1S-2S transition, the authors obtained the Rydberg constant with improved accuracy and an independent value for the proton charge radius that favors the data from muonic hydrogen. However, the present frequency value differs from the one obtained previously using a different spectroscopic technique, leaving the puzzle still unresolved. Science, this issue p. 1061; see also p. 1033 The two-photon 1S-3S transition frequency in H atoms is precisely measured by direct frequency comb spectroscopy below 1 kHz. We have performed two-photon ultraviolet direct frequency comb spectroscopy on the 1S-3S transition in atomic hydrogen to illuminate the so-called proton radius puzzle and to demonstrate the potential of this method. The proton radius puzzle is a significant discrepancy between data obtained with muonic hydrogen and regular atomic hydrogen that could not be explained within the framework of quantum electrodynamics. By combining our result [f1S-3S = 2,922,743,278,665.79(72) kilohertz] with a previous measurement of the 1S-2S transition frequency, we obtained new values for the Rydberg constant [R∞ = 10,973,731.568226(38) per meter] and the proton charge radius [rp = 0.8482(38) femtometers]. This result favors the muonic value over the world-average data as presented by the most recent published CODATA 2014 adjustment.

中文翻译：

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原子氢的双光子频率梳光谱

使用氢原子测试物理学 根据氢和μ子氢光谱数据确定的质子半径之间的差异，即所谓的“质子半径难题”，十多年来一直是物理学界的焦点。使用低于 1 kHz 的双光子紫外频率梳光谱，Grinin 等人。报告了对原子氢中 1S-3S 跃迁频率的高精度测量（参见 Ubachs 的观点）。将这一测量结果与 1S-2S 跃迁的数据相结合，作者获得了里德堡常数，其精度提高了，并且质子电荷半径的独立值有利于来自μ子氢的数据。然而，当前的频率值与之前使用不同光谱技术获得的频率值不同，这使得这个难题仍未解决。科学，这个问题 第1061话 另见第 1033 H 原子中的双光子 1S-3S 跃迁频率是通过 1 kHz 以下的直接频率梳光谱精确测量的。我们对氢原子中的 1S-3S 跃迁进行了双光子紫外直接频率梳光谱，以阐明所谓的质子半径难题并证明该方法的潜力。质子半径难题是用μ子氢和常规原子氢获得的数据之间的显着差异，在量子电动力学的框架内无法解释。通过将我们的结果 [f1S-3S = 2,922,743,278,665.79(72) kHz] 与之前对 1S-2S 跃迁频率的测量相结合，我们获得了里德堡常数的新值 [R∞ = 10,973,731.568226(38) 每米] 和半径 [rp = 0。8482(38) 飞米]。该结果有利于 muonic 值，而不是最近发布的 CODATA 2014 调整所呈现的世界平均数据。