Insight into the narrow structure in η-photoproduction on the neutron from helicity dependent cross sections

Witthauer, L. et al. (2016) Insight into the narrow structure in η-photoproduction on the neutron from helicity dependent cross sections. Physical Review Letters, 117(13), 132505. (doi: 10.1103/PhysRevLett.117.132502) (PMID:27715117)

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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.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Glazier, Dr Derek and MacGregor, Professor Douglas and Livingston, Dr Kenneth and Gardner, Mr Simon and Annand, Dr John and Hamilton, Dr David
Authors: Witthauer, L., Dieterle, M., Abt, S., Achenbach, P., Afzal, F., Ahmed, Z., Annand, J.R.M., Arends, H.J., Bashkanov, M.,, Beck, R., Biroth, M., Borisov, N.S., Braghieri, A., Briscoe, W.J., Cividini, F., Costanza, S., Collicott, C., Denig, A., Downie, E.J., Drexler, P., Ferretti-Bondy, M.I., Gardner, S., Garni, S., Glazier, D.I., Glowa, D., Gradl, W., Günther, M., Gurevich, G.M., Hamilton, D., Hornidge, D., Huber, G.M., Käser, A., Kashevarov, V.L., Kay, S., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Lazarev, A.B., Linturi, J.M., Lisin, V., Livingston, K., Lutterer, S., MacGregor, I.J.D., Mancell, J., Manley, D.M., Martel, P.P., Metag, V., Meyer, W., Miskimen, R., Mornacchi, E., Mushkarenkov, A., Neganov, A.B., Neiser, A., Oberle, M., Ostrick, M., Otte, P.B., Paudyal, D., Pedroni, P., Polonski, A., Prakhov, S.N., Rajabi, A., Reicherz, G., Ron, G., Rostomyan, T., Sarty, A., Sfienti, C., Sikora, M.H., Sokhoyan, V., Spieker, K., Steffen, O., Strakovski, I.I., Strub, T., Supek, I., Thiel, A., Thiel, M., Thomas, A., Unverzagt, M., Usov, Y. A., Wagner, S., Walford, N.K., Watts, D.P., Werthmüller, D., Wettig, J., Wolfes, M., and Zana, L.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Physical Review Letters
Publisher:American Physical Society
ISSN (Online):1079-7114
Published Online:22 September 2016
Copyright Holders:Copyright © 2016 American Physical Society
First Published:First published in Physical Review Letters 117(13):132505
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
570711Nuclear Physics GroupDavid IrelandScience & Technologies Facilities Council (STFC)ST/J000175/1P&A - PHYSICS & ASTRONOMY
507271Illuminating strongly interacting matterI MacgregorScience & Technologies Facilities Council (STFC)ST/G008604/1P&A - PHYSICS & ASTRONOMY