The size of the proton and the deuteron

Randolf Pohl (1) , Fernando D Amaro (2) , Aldo Antognini (3) , François Biraben (4) , João M R Cardoso (5) , Daniel S Covita (6) , Andreas Dax (7) , Satish Dhawan (8) , Luis M P Fernandes (9) , Adolf Giesen (10) , Thomas Graf (10) , Theodor W Hänsch (3) , Paul Indelicato , Lucile Julien (11) , Cheng-Yang Kao (12) , Paul Knowles , Eric-Olivier Le Bigot (13) , Yi-Wei Liu (14) , José a M Lopes (15) , Livia Ludhova , Cristina M B Monteiro (9) , Françoise Mulhauser (16) , Tobias Nebel (3) , François Nez (4) , Paul Rabinowitz (17) , Joaquim M F dos Santos , Lukas A Schaller , Karsten Schuhmann , Catherine Schwob (18) , David Taqqu (19) , João F C A Veloso (9) , Franz Kottmann (20)

1 TU Dresden - Technische Universität Dresden = Dresden University of Technology
2 UERJ - Universidade do Estado do Rio de Janeiro [Brasil] = Rio de Janeiro State University [Brazil] = Université d'État de Rio de Janeiro [Brésil]
3 MPQ - Max-Planck-Institut für Quantenoptik
4 Université Paris 06
5 FEUP - Faculdade de Engenharia da Universidade do Porto
6 Departamento de Fisica [Aveiro]
7 EPFL - Ecole Polytechnique Fédérale de Lausanne
8 Physics Department
9 Departamento de Física
10 IFSW - Institut für Strahwerkzeuge
11 LEG - Laboratoire d'Economie et de Gestion
12 NTHU - National Tsing Hua University [Hsinchu]
13 LKB (Jussieu) - Laboratoire Kastler Brossel
14 IETR - Institut d'Électronique et des Technologies du numéRique
15 CQE - Centro de Quimica Estrutural
16 dpuf - Département de Physique
17 Department of Chemistry
18 INSP - Institut des Nanosciences de Paris
19 PSI - Paul Scherrer Institute
20 ETH Zürich - Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich]

We have recently measured the 2S1/2F=1 − 2P3/2F = 2 energy splitting in the muonic hydrogen atom μp to be 49881.88 (76) GHz. Using recent QED calculations of the fine-, hyperfine, QED and finite size contributions we obtain a root-mean-square proton charge radius of rp = 0.84184 (67) fm. This value is ten times more precise, but 5 standard deviations smaller, than the 2006 CODATA value of rp = 0.8768 (69) fm. The source of this discrepancy is unknown. Using the precise measurements of the 1S-2S transition in regular hydrogen and deuterium and our value of rp we obtain improved values of the Rydberg constant, R∞ = 10973731.568160 (16) m−1and the rms charge radius of the deuteron rd = 2.12809 (31) fm.

Domaines: Physique Atomique [physics.atom-ph]

Randolf Pohl, Fernando D Amaro, Aldo Antognini, François Biraben, João M R Cardoso, et al.. The size of the proton and the deuteron. Journal of Physics: Conference Series, 2011, 264, pp.012008. ⟨10.1088/1742-6596/264/1/012008⟩. ⟨hal-00699025⟩