Insight into the Narrow Structure in eta Photoproduction on the Neutron from Helicity-Dependent Cross Sections

Witthauer, L. and Dieterle, M. and Achenbach, S. and Afzal, F. and Ahmed, Z. and Annand, J. R. M. and Arends, H. J. and Bashkanov, M. and Beck, R. and Biroth, M. and Borisov, N. S. and Braghieri, A. and Briscoe, W. J. and Cividini, F. and Costanza, S. and Collicott, C. and Denig, A. and Downie, E. J. and Drexler, P. and Ferretti-Bondy, M. I. and Gardner, S. and Garni, S. and Glazier, D. I. and Glowa, D. and Gradl, W. and Gunther, M. and Gurevich, G. M. and Hamilton, D. and Hornidge, D. and Huber, G. M. and Kaser, A. and Kashevarov, V. L. and Kay, S. and Keshelashvili, I. and Kondratiev, R. and Korolija, M. and Krusche, B. and Lazarev, A. B. and Linturi, J. M. and Lisin, V. and Livingston, K. and Lutterer, S. and MacGregor, I. J. D. and Mancell, J. and Manley, D. M. and Martel, P. P. and Metag, V. and Meyer, W. and Miskimen, R. and Mornacchi, E. and Mushkarenkov, A. and Neganov, A. B. and Neiser, A. and Oberle, M. and Ostrick, M. and Otte, P. B. and Paudyal, D. and Pedroni, P. and Polonski, A. and Prakhov, S. N. and Rajabi, A. and Reicherz, G. and Ron, G. and Rostomyan, T. and Sarty, A. and Sfienti, C. and Sikora, M. H. and Sokhoyan, V. and Spieker, K. and Steffen, O. and Strakovski, I. I. and Strub, Th. and Supek, I. and Thiel, A. and Thiel, M. and Thomas, A. and Unverzagt, M. and Usov, Yu. A. and Wagner, S. and Walford, N. K. and Watts, D. P. and Werthmuller, D. and Wettig, J. and Wolfes, M. and Zana, L. and Abt, P.. (2016) Insight into the Narrow Structure in eta Photoproduction on the Neutron from Helicity-Dependent Cross Sections. Physical Review Letters, 117 (13). p. 132502.

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Abstract

The double polarization observable E and the helicity dependent cross sections σ1/2 and σ3/2 were measured for η photoproduction from quasifree protons and neutrons. The circularly polarized tagged photon beam of the A2 experiment at the Mainz MAMI accelerator was used in combination with a longitudinally polarized deuterated butanol target. The almost 4π detector setup of the Crystal Ball and TAPS is ideally suited to detect the recoil nucleons and the decay photons from η→2γ and η→3π0. The results show that the narrow structure previously observed in η photoproduction from the neutron is only apparent in σ1/2 and hence, most likely related to a spin-1/2 amplitude. Nucleon resonances that contribute to this partial wave in η production are only N1/2− (S11) and N 1/2+ (P11). Furthermore, the extracted Legendre coefficients of the angular distributions for σ1/2 are in good agreement with recent reaction model predictions assuming a narrow resonance in the P11 wave as the origin of this structure.

Faculties and Departments:	05 Faculty of Science 05 Faculty of Science > Departement Physik 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:	American Physical Society
ISSN:	0031-9007
e-ISSN:	1079-7114
Note:	Publication type according to Uni Basel Research Database: Journal article
Language:	English
Identification Number:	doi: 10.1103/PhysRevLett.117.132502 isi: 000383851400002
edoc DOI:	10.5451/unibas-ep54079
Last Modified:	22 Feb 2017 14:37
Deposited On:	22 Feb 2017 14:36

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