https://doi.org/10.1051/epjconf/202024101002
η’ beam asymmetry at threshold using the BGO-OD experiment
1 Rheinische Friedrich-Willhelms-Universität Bonn, Physikalisches Institut, Nußallee 12, 53115 Bonn, Germany
2 Helmholtz-Institut fuer Strahlen- und Kernphysik, Universitaet Bonn, Nussallee 1-16, D-53115 Bonn Germany
3 Lamar University, Department of Physics, Beaumont, Texas, 77710, USA
4 INFN Roma “Tor Vergata", Rome, Italy
5 Università di Roma “Tor Vergata", Via della Ricerca Scientifica 1, 00133 Rome, Italy
6 INFN sezione di Roma La Sapienza, P.le Aldo Moro 2, 00185 Rome, Italy
7 Istituto Superiore di Sanita, Viale Regina Elena 299, 00161 Rome, Italy
8 Petersburg Nuclear Physics Institute, Gatchina, Leningrad District, 188300, Russia
9 Russian Academy of Sciences Institute for Nuclear Research, prospekt 60-letiya Oktyabrya 7a, Moscow 117312, Russia
10 INFN - Laboratori Nazionali di Frascati, Via E. Fermi 40, 00044, Frascati, Italy
11 INFN sezione Catania, 95129 Catania, Italy
12 Universita degli Studi di Messina, Via Consolato del Mare 41, 98121 Messina, Italy
13 INFN sezione di Pavia, Via Agostino Bassi, 6 - 27100 Pavia, Italy
* Corresponding author: alef@physik.uni-bonn.de
Published online: 22 September 2020
The unexpected nodal structure of the beam asymmetry recently reported by the GRAAL collaboration in η′ photoproduction very close to threshold could be explained by a previously unobserved narrow resonance. The BGO-OD experiment is ideally suited to verify this measurement via the detection of forward going charged particles which in the threshold region of interest allows the identification of the reaction γp → η′ p solely based on the proton going in the forward direction. This yields unprecedented statistics if, in the missing mass analysis of the η′ meson, the background can be sufficiently well controlled. Preliminary results using a linearly polarised photon beam are shown. The reaction γp → η′ p was identified in the BGO forward spectrometer, with simulated data used to seperate signal and background.
© The Authors, published by EDP Sciences, 2020
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
