Proton size puzzle reinforced!

January 20, 2013

These results have puzzled the world three years ago: the size of the proton (to be precise, its charge radius), spectroscopically measured in exotic hydrogen in which the electron orbiting the nucleus is replaced by a negatively charged muon, yielded a value significantly smaller than the one from previous investigations of regular hydrogen or electron-proton-scattering. A new measurement by the same team again using a thin-disk laser from the Institut für Strahlwerkzeuge (IFW) of the University of Stuttgart confirms the value of the electric charge radius and makes it possible for the first time to determine the magnetic radius of the proton with laser spectroscopy of muonic hydrogen.

Original Publication:
Aldo Antognini, François Nez, Karsten Schuhmann, Fernando D. Amaro, François Biraben, João M. R. Cardoso, Daniel S. Covita, Andreas Dax, Satish Dhawan, Marc Diepold, Luis M. P. Fernandes, Adolf Giesen, Andrea L. Gouvea, Thomas Graf, Theodor W. Hänsch, Paul Indelicato, Lucile Julien, Cheng-Yang Kao, Paul Knowles, Franz Kottmann, Eric-Olivier Le Bigot, Yi-Wei Liu, José A. M. Lopes, Livia Ludhova, Cristina M. B. Monteiro, Françoise Mulhauser, Tobias Nebel, Paul Rabinowitz, Joaquim M. F. dos Santos, Lukas A. Schaller, Catherine Schwob, David Taqqu, João F. C. A. Veloso, Jan Vogelsang, Randolf Pohl    
Proton structure from the measurement of 2S − 2P transition frequencies of muonic hydrogen   
Science. 25. Januar 2013

Contact: Prof. Dr. Thomas Graf

To the top of the page