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arXiv · 2111.08554

Measurement of the $2$S$_{1/2}-8$D$_{5/2}$ transition in hydrogen

A. D. Brandt·S. F. Cooper·C. Rasor·Z. Burkley·D. C. Yost·A. Matveev
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Abstract

We present a measurement of the hydrogen $2$S$_{1/2}-8$D$_{5/2}$ transition performed with a cryogenic atomic beam. The measured resonance frequency is $\nu=770649561570.9(2.0)$ kHz, which corresponds to a relative uncertainty of $2.6\times10^{-12}$. Combining our result with the most recent measurement of the $1$S$-2$S transition, we find a proton radius of $r_p=0.8584(51)$~fm and a Rydberg constant of $R_\infty=10973731.568332(52)$ m$^{-1}$. This result has a combined 3.1~$\sigma$ disagreement with the CODATA 2018 recommended value. Possible implications of the discrepancy are discussed.

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A. D. Brandt, S. F. Cooper, C. Rasor, Z. Burkley, D. C. Yost, A. Matveev. 2021-11-16. Measurement of the $2$S$_{1/2}-8$D$_{5/2}$ transition in hydrogen. https://doi.org/10.1103/physrevlett.128.023001

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