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The size of the proton

Pohl, Randolf and Antognini, Aldo and Nez, Francois and Amaro, Fernando and Biraben, Francois and Cardoso, Joao and Covita, Daniel and Dax, Andreas and Dhawan, Satish and Fernandes, Luis and Giesen, Adolf and Graf, Thomas and Hänsch, Theodor and Indelicato, Paul and Julien, Lucile and Kao, Cheng-Yang and Knowles, Paul and Le Bigot, Eric and Liu, Yi-Wei and Lopes, Jose and Ludhova, Livia and Monteiro, Christina and Mulhauser, Francoise and Nebel, Tobias and Rabinowitz, Paul and dos Santos, Joaquim and Schaller, Lukas and Schuhmann, Karsten and Schwob, Catherine and Taqqu, David and Veloso, Joao and Kottmann, Franz (2010) The size of the proton. Nature, 466, pp. 213-217. Nature Publishing Group. DOI: 10.1038/nature09250

Full text not available from this repository.

Abstract

The proton is the primary building block of the visible Universe, but many of its properties—such as its charge radius and its anomalous magneticmoment—are not well understood. The root-meansquare charge radius, rp, has been determined with an accuracy of 2 per cent (at best) by electron–proton scattering experiments. The present most accurate value of rp (with an uncertainty of 1 per cent) is given by the CODATA compilation of physical constants. This value is based mainly on precision spectroscopy of atomic hydrogen and calculations of bound-state quantum electrodynamics. The accuracy of rp as deduced from electron–proton scattering limits the testing of bound-state QED in atomic hydrogen as well as the determination of the Rydberg constant (currently the most accurately measured fundamental physical constant). An attractive means to improve the accuracy in themeasurement of rp is provided bymuonic hydrogen (a proton orbited by a negative muon); its much smaller Bohr radius compared to ordinary atomic hydrogen causes enhancement of effects related to the finite size of the proton. In particular, theLamb shift (the energy difference between the 2S1/2 and 2P1/2 states) is affected by as much as 2 per cent. Here we use pulsed laser spectroscopy to measure a muonic Lamb shift of 49,881.88(76)GHz. On the basis of present calculations of fine and hyperfine splittings and QED terms, we find rp 50.84184(67) fm, which differs by 5.0 standard deviations from the CODATA value of 0.8768(69) fm. Our result implies that either the Rydberg constant has to be shifted by 2110 kHz/c (4.9 standard deviations), or the calculations of the QED effects in atomic hydrogen or muonic hydrogen atoms are insufficient.

Item URL in elib:https://elib.dlr.de/64637/
Document Type:Article
Title:The size of the proton
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Pohl, RandolfMax Plank Institut für QuantenoptikUNSPECIFIED
Antognini, AldoMax Plank Institut für QuantenoptikUNSPECIFIED
Nez, FrancoisLaboratoire Kastler BrosselUNSPECIFIED
Amaro, FernandoUniversidade de CoimbraUNSPECIFIED
Biraben, FrancoisLaboratoire Kastler BrosselUNSPECIFIED
Cardoso, JoaoUniversidade de CoimbraUNSPECIFIED
Covita, DanielUniversidade de CoimbraUNSPECIFIED
Dax, AndreasYale UniversityUNSPECIFIED
Dhawan, SatishYale UniversityUNSPECIFIED
Fernandes, LuisUniversidade de CoimbraUNSPECIFIED
Giesen, AdolfUNSPECIFIEDUNSPECIFIED
Graf, ThomasInstitut für StrahlwerkzeugeUNSPECIFIED
Hänsch, TheodorMax Plank Institut für QuantenoptikUNSPECIFIED
Indelicato, PaulLaboratoire Kastler BrosselUNSPECIFIED
Julien, LucileLaboratoire Kastler BrosselUNSPECIFIED
Kao, Cheng-YangTsing Hua University, TaiwanUNSPECIFIED
Knowles, PaulUniversity de FribourgUNSPECIFIED
Le Bigot, EricLaboratoire Kastler BrosselUNSPECIFIED
Liu, Yi-WeiNational Tsing Hua UniversityUNSPECIFIED
Lopes, JoseUniversidade de CoimbraUNSPECIFIED
Ludhova, LiviaUniversity de FribourgUNSPECIFIED
Monteiro, ChristinaUniversidade de CoimbraUNSPECIFIED
Mulhauser, FrancoiseUniversity de FribourgUNSPECIFIED
Nebel, TobiasMax Plank Institut für QuantenoptikUNSPECIFIED
Rabinowitz, PaulPrinceton UniversityUNSPECIFIED
dos Santos, JoaquimUniversidade de CoimbraUNSPECIFIED
Schaller, LukasUniversity de FribourgUNSPECIFIED
Schuhmann, KarstenTechnologiegesellschaft für StrahlwerkzeugeUNSPECIFIED
Schwob, CatherineLaboratoire Kastler BrosselUNSPECIFIED
Taqqu, DavidPaul Scherrer InstituteUNSPECIFIED
Veloso, JoaoUniveristy of Aveiro, PortugalUNSPECIFIED
Kottmann, FranzPaul Scherrer InstituteUNSPECIFIED
Date:8 July 2010
Journal or Publication Title:Nature
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:466
DOI :10.1038/nature09250
Page Range:pp. 213-217
Publisher:Nature Publishing Group
Series Name:Letters
Status:Published
Keywords:proton size
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:Aircraft Research (old)
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Laser Research and Technology (old)
Location: Stuttgart
Institutes and Institutions:Institute of Technical Physics
Deposited By: Eckel, Dr.rer.nat. Hans-Albert
Deposited On:08 Jul 2010 11:33
Last Modified:08 Mar 2018 18:47

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