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Sunday, 22 October, 2017

Shrinking the proton again

Quantum physics

Laser spectroscopy. Picture: MPQ

Laser spectroscopy. Picture: MPQ

High precision laser spectroscopy analysis of atomic hydrogen confirmed the surprisingly small value of the proton radius determined from muonic hydrogen. This was proven by the NIM Prof Theodor Hänsch and colleagues at the Max Planck Institute of Quantum Optics (MPQ) in Garching.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly smaller, by four standard deviations, than previous determinations using regular hydrogen. This discrepancy and its origin have attracted much attention in the scientific community, with even extensions of the so-called standard model of physics being discussed.

Now, a team of scientists from the Laser Spectroscopy Division of Professor Opens external link in new windowTheodor W Hänsch (NIM, LMU and MPQ) has made a new spectroscopic measurement of regular hydrogen. The resulting values for the Rydberg constant and the proton radius are in excellent agreement with the muonic results, but disagree by 3.3 standard deviations with the average of the previous determinations from regular hydrogen.

Full Opens external link in new windowpress release of the Max Planck Institute of Quantum Optics



The Rydberg constant and proton size from atomic hydrogen. Axel Beyer, Lothar Maisenbacher, Arthur Matveev, Randolf Pohl, Ksenia Khabarova, Alexey Grinin, Tobias Lamour, Dylan C. Yost, Theodor W. Hänsch, Nikolai Kolachevsky, Thomas Udem. Science 06 Oct 2017: Vol. 358, Issue 6359, pp. 79-85; DOI: Opens external link in new window10.1126/science.aah667


Prof Dr Theodor W Hänsch
Ludwig-Maximilians-Universität München
Carl Friedrich von Siemens-Professor of Physics
Director of the Max Planck Institute for Quantum Optics
Schellingstr. 4/III
80799 Munich

Phone: +49 89 2180 3212

E-Mail: Opens window for sending emailt.w.haensch(at)physik.uni-muenchen.de

Web: Opens external link in new windowwww2.mpq.mpg.de/~haensch/htm_neu/research.html


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