Helicity-dependent cross sections and double-polarization observable E in η photoproduction from quasifree protons and neutrons

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dc.contributor.author Witthauer, L.
dc.contributor.author Dieterle, M.
dc.contributor.author Abt, S.
dc.contributor.author Achenbach, P.
dc.contributor.author Afzal, F.
dc.contributor.author Ahmed, Z.
dc.contributor.author Akondi, C. S.
dc.contributor.author Annand, J. R. M.
dc.contributor.author Arends, H. J.
dc.contributor.author Bashkanov, M.
dc.contributor.author Beck, R.
dc.contributor.author Biroth, M.
dc.contributor.author Borisov, N. S.
dc.contributor.author Braghieri, A.
dc.contributor.author Briscoe, W. J.
dc.contributor.author Cividini, F.
dc.contributor.author Costanza, S.
dc.contributor.author Collicott, C.
dc.contributor.author Denig, A.
dc.contributor.author Downie, E. J.
dc.contributor.author Drexler, P.
dc.contributor.author Ferretti-Bondy, M. I.
dc.contributor.author Gardner, S.
dc.contributor.author Garni, S.
dc.contributor.author Glazier, D. I.
dc.contributor.author Glowa, D.
dc.contributor.author Gradl, W.
dc.contributor.author Günther, M.
dc.contributor.author Gurevich, G. M.
dc.contributor.author Hamilton, D.
dc.contributor.author Hornidge, D.
dc.contributor.author Huber, G. M.
dc.contributor.author Käser, A.
dc.contributor.author Kashevarov, V. L.
dc.contributor.author Kay, S.
dc.contributor.author Keshelashvili, I.
dc.contributor.author Kondratiev, R.
dc.contributor.author Krusche, B.
dc.contributor.author Lazarev,A. B.
dc.contributor.author Linturi, James M.
dc.contributor.author Lisin, V.
dc.contributor.author Livingston, K.
dc.contributor.author Lutterer, S.
dc.contributor.author MacGregor, I. J. D.
dc.contributor.author Mancell, J.
dc.contributor.author Manley, D. M.
dc.contributor.author Martel, P. P.
dc.contributor.author Metag, V.
dc.contributor.author Meyer, W.
dc.contributor.author Miskimen, R.
dc.contributor.author Mornacchi, E.
dc.contributor.author Mushkarenkov, A.
dc.contributor.author Neganov, A. B.
dc.contributor.author Neiser, A.
dc.contributor.author Oberle, M.
dc.contributor.author Ostrick, M.
dc.contributor.author Otte, P. B.
dc.contributor.author Paudyal, D.
dc.contributor.author Pedroni, P.
dc.contributor.author Polonski, A.
dc.contributor.author Prakhov, S. N.
dc.contributor.author Rajabi, A.
dc.contributor.author Reicherz, G.
dc.contributor.author Ron, G.
dc.contributor.author Rostomyan, T.
dc.contributor.author Sarty, A.
dc.contributor.author Sfienti, C.
dc.contributor.author Sikora, M. H.
dc.contributor.author Sokhoyan, V.
dc.contributor.author Spieker, K.
dc.contributor.author Steffen, O.
dc.contributor.author Strakovsky, I. I.
dc.contributor.author Strub, Th.
dc.contributor.author Supek, I.
dc.contributor.author Thiel, A.
dc.contributor.author Thiel, M.
dc.contributor.author Thomas, A.
dc.contributor.author Unverzagt, M.
dc.contributor.author Usov, Yu. A.
dc.contributor.author Wagner, S.
dc.contributor.author Walford, N. K.
dc.contributor.author Watts, D. P.
dc.contributor.author Werthmüller, D.
dc.contributor.author Wettig, J.
dc.contributor.author Wolfes, M.
dc.contributor.author Zana, L.
dc.date.accessioned 2018-02-08T09:38:52Z
dc.date.available 2018-02-08T09:38:52Z
dc.date.issued 2017-05-01
dc.identifier.citation Physical Review C, 95, 055201 en_US
dc.identifier.issn 2469-9985
dc.identifier.uri https://journals.aps.org/prc/pdf/10.1103/PhysRevC.95.055201
dc.identifier.uri http://repository.seku.ac.ke/handle/123456789/3838
dc.description DOI:https://doi.org/10.1103/PhysRevC.95.055201 en_US
dc.description.abstract Precise helicity-dependent cross sections and the double-polarization observable E were measured for η photoproduction from quasifree protons and neutrons bound in the deuteron. The η → 2γ and η → 3π0 → 6γ decay modes were used to optimize the statistical quality of the data and to estimate systematic uncertainties. The measurement used the A2 detector setup at the tagged photon beam of the electron accelerator MAMI in Mainz. A longitudinally polarized deuterated butanol target was used in combination with a circularly polarized photon beam from bremsstrahlung of a longitudinally polarized electron beam. The reaction products were detected with the electromagnetic calorimeters Crystal Ball and TAPS, which covered 98% of the full solid angle. The results show that the narrow structure observed earlier in the unpolarized excitation function of η photoproduction off the neutron appears only in reactions with antiparallel photon and nucleon spin (σ1/2). It is absent for reactions with parallel spin orientation (σ3/2) and thus very probably related to partial waves with total spin 1/2. The behavior of the angular distributions of the helicity-dependent cross sections was analyzed by fitting them with Legendre polynomials. The results are in good agreement with a model from the Bonn-Gatchina group, which uses an interference of P11 and S11 partial waves to explain the narrow structure. en_US
dc.language.iso en en_US
dc.publisher American Physical Society en_US
dc.title Helicity-dependent cross sections and double-polarization observable E in η photoproduction from quasifree protons and neutrons en_US
dc.type Article en_US

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