München 2019 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 25: Hadron Structure and Spectroscopy IV

HK 25.4: Vortrag

Dienstag, 19. März 2019, 17:30–17:45, HS 13

Proton Radius in High-Energy Muon Scattering — •Christian Dreisbach¹, Jan Friedrich¹, Martin Hoffmann², Alexander Inglessi³, Eva Kabuss⁴, Bernhard Ketzer², Oleg Kiselev⁶, Evgeny Maev³, Stephan Paul¹, Sebastian Uhl¹, Benjamin Veit^5,6, and the COMPASS Collaboration⁵ — ¹Technische Universität München, Physik-Department, Garching, Germany — ²Universität Bonn, Helmholtz-Institut für Strahlen- und Kernphysik, Bonn, Germany — ³Petersburg Nuclear Physics Institute (PNPI), Gatchina, Russia — ⁴Universität Mainz, Institut für Kernphysik, Mainz, Germany — ⁵CERN, 1211 Geneva 23, Switzerland — ⁶GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany

The proton radius can be determined by measuring the slope of the electric form factor G_E at small squared four-momentum transfer Q². Numerous elastic-scattering and laser-spectroscopy measurements of the proton radius have been performed with contradicting results, the so-called proton radius puzzle. We propose to measure the proton radius in high-energy elastic muon-proton scattering at the M2 beam line of CERN*s Super Proton Synchrotron in the year 2022. A high-precision measurement at low Q² realized with a high-pressure hydrogen TPC can contribute to a solution of the puzzle, especially in view of the systematics of this approach compared to electron scattering. In the year 2018, a test measurement with silicon tracking detectors upstream and downstream of a prototype TPC was performed to study the feasibility employing both detector systems. We present results of the on-going analysis and discuss ideas for a possible setup in 2022.