Bochum 2018 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 37: Hadron Structure and Spectroscopy VI

HK 37.1: Group Report

Wednesday, February 28, 2018, 16:30–17:00, HZO 50

Production of pseudoscalar mesons in proton-deuteron fusion with WASA-at-COSY — •Nils Hüsken, Kay Demmich, and Alfons Khoukaz for the WASA-at-COSY collaboration — Westfälische Wilhelms-Universität Münster

The production of pseudoscalar mesons in the proton-deuteron fusion to ³HeX final states has received considerable interest in the past. In the production of η mesons, a strong final state interaction leads to an unexpected enhancement of the total cross section right at the production threshold. While this effect has been studied extensively already, the main production mechanism remains largely unexplored. A new dataset gathered with the WASA experiment, located inside the COSY accelerator complex, at 15 different excess energies between Q_η=13 MeV and Q_η=81 MeV (corresponding to p_p=1.60 GeV/c up to p_p=1.74 GeV/c) provides new insight both in the transition region where the final state interaction loses its importance, as well as into the region where the production mechanism is dominant. In addition, also the production of pions is studied. Within the accessible energy region, thus far only data for collinear single-pion production exists, exhibiting significant structures in both the cross section as well as in the contributing amplitudes and the tensor polarization in the backward direction. With the new dataset, a large part of the backward hemisphere is covered and detailed differential cross sections are extracted. This marks the first time, such data is available in this energy region. Recent results on both the η and the π⁰ production will be reported and an outlook will be given on future possibilities.