Photoproduction of η mesons from the neutron: Cross sections and double polarization observable E

Witthauer, L. and Dieterle, M. and Afzal, F. and Anisovich, A. V. and Bantes, B. and Bayadilov, D. and Beck, R. and Bichow, M. and Brinkmann, K. -T. and Boese, S. and Challand, Th. and Crede, V. and Dutz, H. and Eberhardt, H. and Elsner, D. and Ewald, R. and Fornet-Ponse, K. and Friedrich, St. and Frommberger, F. and Funke, Ch. and Goertz, St. and Gottschall, M. and Gridnev, A. and Gruener, M. and Gutz, E. and Hammann, D. and Hammann, Ch. and Hannappel, J. and Hartmann, J. and Hillert, W. and Hoffmeister, Ph. and Honisch, Ch. and Jude, T. and Kaiser, D. and Kalinowsky, H. and Kalischewski, F. and Kammer, S. and Kaser, A. and Keshelashvili, I. and Klassen, P. and Kleber, V. and Klein, F. and Koop, K. and Krusche, B. and Lang, M. and Lopatin, I. and Mahlberg, Ph. and Makonyi, K. and Metag, V. and Meyer, W. and Mueller, J. and Muellers, J. and Nanova, M. and Nikonov, V. and Piontek, D. and Reicherz, G. and Rostomyan, T. and Sarantsev, A. and Schmidt, Ch. and Schmieden, H. and Seifen, T. and Sokhoyan, V. and Spieker, K. and Thiel, A. and Thoma, U. and Urban, M. and van Pee, H. and Walford, N. K. and Walther, D. and Wendel, Ch. and Werthmueller, D. and Wilson, A. and Winnebeck, A.. (2017) Photoproduction of η mesons from the neutron: Cross sections and double polarization observable E. European Physical Journal A: Hadrons and Nuclei , 53 (3). p. 58.

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Abstract

Results from measurements of the photoproduction of η mesons from quasifree protons and neutrons are summarized. The experiments were performed with the CBELSA/TAPS detector at the electron accelerator ELSA in Bonn using the η→3π0→6γ decay. A liquid deuterium target was used for the measurement of total cross sections and angular distributions. The results confirm earlier measurements from Bonn and the MAMI facility in Mainz about the existence of a narrow structure in the excitation function of γn→nη. The current angular distributions show a forward-backward asymmetry, which was previously not seen, but was predicted by model calculations including an additional narrow P11 state. Furthermore, data obtained with a longitudinally polarized, deuterated butanol target and a circularly polarized photon beam were analyzed to determine the double polarization observable E. Both data sets together were also used to extract the helicity-dependent cross sections σ1/2 and σ3/2. The narrow structure in the excitation function of γn→nη appears associated with the helicity-1/2 component of the reaction.

Faculties and Departments:	05 Faculty of Science > Departement Physik > Former Organization Units Physics > Hadronenphysik (Krusche)
UniBasel Contributors:	Krusche, Bernd
Item Type:	Article, refereed
Article Subtype:	Research Article
Publisher:	EDP Sciences with Springer and Società Italiana di Fisica
ISSN:	1434-6001
e-ISSN:	1434-601X
Note:	Publication type according to Uni Basel Research Database: Journal article
Identification Number:	doi: 10.1140/epja/i2017-12247-0 isi: 000403579200001
Last Modified:	15 Jan 2018 14:02
Deposited On:	15 Jan 2018 14:02

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