Darmstadt 2016 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

HK: Fachverband Physik der Hadronen und Kerne

HK 46: Hauptvorträge II

HK 46.2: Hauptvortrag

Donnerstag, 17. März 2016, 11:45–12:15, S1/01 A1

Ever-changing proton radius?! — •Miha Mihovilovic — Institut für Kernphysik, Johannes-Gutenberg-Universität, Johann-Joachim-Becher-Weg 45, D-55128 Mainz, Germany

The discrepancy between the proton charge radius extracted from the muonic hydrogen Lamb shift measurement and the presently best value obtained from elastic scattering experiments remains unexplained and represents a burning problem of today's nuclear physics. Therefore, several new experiments are underway, committed to provide new insight into the problem. High-precision electron scattering experiments are in progress at the Jefferson Lab and the Mainz Microtron. As a counterpart to these measurements, a muon-proton scattering experiment is envisioned at the Paul Scherrer Institute. Together with the nuclear scattering experiments, new atomic measurements are underway at the Max Planck Institute in Garching, which aim to further improve also the spectroscopic results on electronic hydrogen. These experiments are complemented by extensive theoretical efforts focused on studying various processes contributing to the atomic Lamb shift measurements that could explain the difference, as well as on pursuing different ways to interpret nuclear form-factor measurements, which could lead to a consistent value of the radius.

In this presentation the currently best proton radius measurements will be summarized, and the importance of the observed inconsistency between the hydrogen and the muonic-hydrogen data will be discussed. Selected new experiments dedicated to remeasuring the radius will be described, and the results of the MAMI experiment will be presented.