Physics of our days

Proton charge radius

  a,  a, b
a Lebedev Physical Institute, Russian Academy of Sciences, Leninsky prosp. 53, Moscow, 119991, Russian Federation
b International Center for Quantum Optics and Quantum Technologies (the Russian Quantum Center), ul. Novaya 100, Skolkovo, Moscow Region, 143025, Russian Federation

The so-called proton charge radius puzzle was one of the challenging problems in physics in the last decade. A significant (at the level of four standard deviations (4σ) difference between the values of the root-mean-square proton charge radius measured in normal and muonic hydrogen has kindled lively discussions among both experimentalists and theoreticians specializing in quantum electrodynamics. The problem becomes even more glaring (up to 7σ) if data on the scattering of electrons on protons are taken into account. We review various methods that enable measurement of the proton charge radius, analyze the origin of the disagreement, and present results of recent experiments that aim at resolving this puzzle.

Typically, an English fulltext is available in about 3 months from the date of publication of the original article.

Keywords: proton radius, hydrogen atom, muonic hydrogen, proton radius puzzle, Rydberg constant, single-photon spectroscopy, e-p scattering
PACS: 06.20.Jr, 06.30.Ft, 12.20.Fv, 32.10.Fn, 32.30.Jc, 42.62.Fi (all)
DOI: 10.3367/UFNe.2021.06.038986
Citation: Khabarova K Yu, Kolachevsky N N "Proton charge radius" Phys. Usp. 64 (10) (2021)

Received: 11th, February 2021, revised: 4th, June 2021, 6th, June 2021

Оригинал: Хабарова К Ю, Колачевский Н Н «Зарядовый радиус протона» УФН 191 1095–1106 (2021); DOI: 10.3367/UFNr.2021.06.038986

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