The size of the proton

@article{Pohl2010TheSO,
  title={The size of the proton},
  author={Randolf Pohl and Aldo Antognini and François Nez and Fernando Domingues Amaro and Francois Biraben and Jo{\~a}o M. R. Cardoso and Daniel S. Covita and Andreas J Dax and S. K. Dhawan and Luis M P Fernandes and Adolf Giesen and Thomas Graf and Theodor W. H{\"a}nsch and Paul Indelicato and Lucile Julien and Cheng-Yang Kao and Paul E. Knowles and E.-O. Le Bigot and Yi-Wei Liu and Jos{\'e} A. M. Lopes and Livia Ludhova and Cristina Maria Bernardes Monteiro and Françoise Mulhauser and Tobias Nebel and Paul Rabinowitz and Joaquim M.F. dos Santos and Lukas A. Schaller and Karsten Schuhmann and Catherine Schwob and David Taqqu and Jo{\~a}o Veloso and Franz Kottmann},
  journal={Nature},
  year={2010},
  volume={466},
  pages={213-216}
}
The proton is the primary building block of the visible Universe, but many of its properties—such as its charge radius and its anomalous magnetic moment—are not well understood. The root-mean-square 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… 
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Measurement of the proton Zemach radius from the hyperfine splitting in muonic hydrogen atom
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