Bonn 2020 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 55: Hadron Structure and Spectroscopy IX

HK 55.3: Talk

Friday, April 3, 2020, 11:45–12:00, J-HS A

Determination of the target asymmetry T in the reaction γ p → pπ⁰ — •Sebastian Ciupka for the CBELSA/TAPS collaboration — Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn

Photoproduction experiments provide a tool to further our understanding of the experimentally observed nucleon excitation spectra, which show discrepancies to predictions based on e.g. lattice QCD. Since the resonances are strongly overlapping, a partial wave analysis is needed to disentangle the states. To unambiguously determine the complex amplitudes of the analysis, it is not enough to conduct unpolarised measurements, therefore measurements with a polarised beam, a polarised target or with a recoil nucleon polarimeter have to be realised.

At the CBELSA/TAPS experiment in Bonn a linearly or circularly polarised photon beam and a longitudinally or transversely polarised target are provided, giving access to single and double polarization observables. The two main detectors of the experiment are the Crystal Barrel (CB) calorimeter and the MiniTAPS calorimeter in forward direction, which in combination provide nearly 4π coverage.
This talk presents preliminary results for the target asymmetry T in π⁰ photoproduction, determined from data collected after the upgrade of the CB readout system at the end of 2017. The data are compared with previously collected data and theoretical predictions.