Dresden 2013 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 42: Hadronenstruktur und -spektroskopie
HK 42.4: Talk
Tuesday, March 5, 2013, 17:45–18:00, HSZ-304
Measurement of the Proton Scalar Polarizabilities at MAMI — •Vahe Sokhoyan — George Washington University, Washington, USA — Institut für Kernphysik, Universität Mainz, Germany
The scalar polarizabilities, αE1 and βM1, are fundamental properties of the nucleon. They play a crucial role not only in our understanding of the nucleon, but also in other areas such as atomic physics, where they provide e.g. corrections to the Lamb Shift. Recent analyses suggest significant model dependence in the extraction of αE1 and βM1. To date, these observables were extracted in parallel from unpolarized cross-sections of Compton scattering on the proton. At the MAMI accelerator facility in Mainz, the nucleon polarizabilities will be measured using a linearly polarized photon beam for the first time in a photon energy range from 110 to 150 MeV. The beam will impinge on a liquid Hydrogen target and the reaction products will be detected in the Crystal Ball and TAPS 4π spectrometer setup. This measurement will allow for the first independent extraction of the observables αE1 and βM1 using real Compton scattering on the proton below pion threshold. In the talk the current status of the αE1 and βM1 measurement will be presented. In addition the current status of the investigation of dilepton photoproduction off the proton, which will be measured in parallel due to the necessarily open trigger conditions, will be discussed.