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HK: Fachverband Physik der Hadronen und Kerne

HK 25: Hadron Structure and Spectroscopy IV

HK 25.2: Vortrag

Dienstag, 19. März 2019, 17:00–17:15, HS 13

News from the "proton radius puzzle" — •Randolf Pohl for the CREMA collaboration — JGU Mainz, Germany

For more than eight years now, the "proton radius puzzle" has let us dream about new physics: Our measurements of muonic hydrogen and muonic deuterium, performed in the CREMA Collaboration at PSI, yielded a proton radius which is more than five standard deviations smaller than the CODATA world average from measurements using electrons, namely precision spectroscopy of atomic hydrogen and deuterium, and elastic electron scattering.

A wealth of new experiments has been fueled by this exciting discrepancy, and the first results are now coming in. I will report on several new measurements in atomic hydrogen we have performed at MPQ Garching. These, together with new hydrogen measurements from LKB Paris and York U. Toronto and new elastic electron scattering data from the PRad experiment at Jefferson Lab start to paint a clearer picture on the "proton radius puzzle", albeit not without raising new questions.