Review of experimental and theoretical status of the proton radius puzzle

Richard J. Hill, Y. Foka, N. Brambilla, V. Kovalenko
2017 EPJ Web of Conferences  
The discrepancy between the measured Lamb shift in muonic hydrogen and expectations from electron-proton scattering and regular hydrogen spectroscopy has become known as the proton radius puzzle, whose most "mundane" resolution requires a $> 5 \sigma$ shift in the value of the fundamental Rydberg constant. I briefly review the status of spectroscopic and scattering measurements, recent theoretical developments, and implications for fundamental physics.
doi:10.1051/epjconf/201713701023 fatcat:2tjxd7kmrbhorpyzcax43hca3a