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The size of the proton and the deuteron

2011; IOP Publishing; Volume: 264; Linguagem: Inglês

10.1088/1742-6596/264/1/012008

1742-6596

Randolf Pohl, F. D. Amaro, Aldo Antognini, F. Biraben, J. M. R. Cardoso, D. S. Covita, A. Dax, S. Dhawan, L. M. P. Fernandes, Adolf Giesen, Thomas Graf, T. W. Hänsch, P. Indelicato, L. Julién, Cheng-Yang Kao, Paul Knowles, Éric-Olivier Le Bigot, Yiwei Liu, J. A. M. Lopes, L. Ludhová, C.M.B. Monteiro, F. Mulhauser, Tobias Nebel, F. Nez, Paul Rabinowitz, J.M.F. dos Santos, L. A. Schaller, Karsten Schuhmann, Catherine Schwob, D. Taqqu, J.F.C.A. Veloso, F. Kottmann,

Scientific Research and Discoveries

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.