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HK: Fachverband Physik der Hadronen und Kerne

HK 47: Hadron Structure and Spectroscopy VI

HK 47.1: Group Report

Wednesday, March 13, 2024, 15:45–16:15, HBR 62: EG 19

Multi-meson photoproduction with the CBELSA/TAPS experiment — •Tobias Seifen for the CBELSA/TAPS collaboration — Helmholtz-Institut für Strahlen- und Kernphysik, Nussallee 14-16, 53115 Bonn

One important step in understanding the baryon spectrum is a precise knowledge of the excited states and their decays. In order to extract the contributing resonances from experimental data a partial wave analysis needs to be performed. To resolve ambiguities, the measurement of polarization observables is indispensable. In the regime of high-mass baryon resonances multi-meson final states are of particular importance. Here sequential decays of resonances are observed.

The CBELSA/TAPS experiment is ideally suited to measure the photoproduction of neutral mesons decaying into photons due to its good energy resolution, high detection efficiency for photons, and the nearly complete solid angle coverage. In combination with a longitudinally or transversely polarized target and an energy tagged, linearly or circularly polarized photon beam the experiment allows the measurement of a large set of polarization observables.

This talk will focus on results on neutral double pion production obtained with a linearly polarized photon beam and either an unpolarized hydrogen target or a transversely polarized butanol target. Part of the results were included in the Bonn-Gatchina partial wave analysis. Observed systematic differences in the branching ratios for decays of N^* and Δ^* resonances are attributed to the internal structure of these excited nucleon states.

Keywords: polarization observables; meson photoproduction; baryon spectroscopy