The isospin structure of photoproduction of πη pairs from the nucleon in the threshold region

Käser, A. et al. (2015) The isospin structure of photoproduction of πη pairs from the nucleon in the threshold region. Physics Letters B, 748, pp. 244-250. (doi:10.1016/j.physletb.2015.07.007)

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Abstract

Photoproduction of πη -pairs from nucleons has been investigated from threshold up to incident photon energies of ≈ 1.4 GeV. The quasi-free reactions γp→pπ0η, γn→nπ0η, γp→nπ+η, and γn→pπ−η were for the first time measured from nucleons bound in the deuteron. The corresponding reactions from a free-proton target were also studied to investigate final-state interaction effects (for neutral pions the free-proton results could be compared to previous measurements; the γp→nπ+η reaction was measured for the first time). For the π0η final state coherent production via the γd→dπ0η reaction was also investigated. The experiments were performed at the tagged photon beam of the Mainz MAMI accelerator using an almost 4π coverage electromagnetic calorimeter composed of the Crystal Ball and TAPS detectors. The total cross sections for the four different final states obey the relation σ(pπ0η)≈σ(nπ0η)≈2σ(pπ−η)≈2σ(nπ+η) as expected for a dominant contribution from a Δ⋆→ηΔ(1232)→πηN reaction chain, which is also supported by the shapes of the invariant-mass distributions of nucleon–meson and π–η pairs. The experimental results are compared to the predictions from an isobar reaction model.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Glazier, Dr Derek and McGeorge, Dr John and Robinson, Mr Jamie and MacGregor, Professor I and Livingston, Dr Kenneth and Howdle, Mr David and Annand, Dr John and Hamilton, Dr David and Rosner, Professor Guenther
Authors: Käser, A., Ahrens, J., Annand, J.R.M., Arends, H.J., Bantawa, K., Bartolome, P.A., Beck, R., Bekrenev, V., Berghäuser, H., Braghieri, A., Branford, D., Briscoe, W.J., Brudvik, J., Cherepnya, S., Costanza, S., Demissie, B., Dieterle, M., Downie, E.J., Drexler, P., Fil'kov, L.V., Fix, A., Glazier, D.I., Hamilton, D., Heid, E., Hornidge, D., Howdle, D., Huber, G.M., Jahn, O., Jaegle, I., Jude, T.C., Kashevarov, V.L., Keshelashvili, I., Kondratiev, R., Korolija, M., Kruglov, S.P., Krusche, B., Lisin, V., Livingston, K., MacGregor, I.J.D., Maghrbi, Y., Mancell, J., Manley, D.M., Marinides, Z., McGeorge, J.C., McNicoll, E., Mekterovic, D., Metag, V., Micanovic, S., Middleton, D.G., Mushkarenkov, A., Nikolaev, A., Novotny, R., Oberle, M., Ostrick, M., Otte, P., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Prakhov, S.N., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M.H., Sober, D.I., Starostin, A., Supek, I., Thiel, M., Thomas, A., Unverzagt, M., Watts, D.P., Werthmüller, D., and Witthauer, L.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Physics Letters B
Publisher:Elsevier BV
ISSN:0370-2693
ISSN (Online):1873-2445
Copyright Holders:Copyright © 2015 The Authors
First Published:First published in Physics Letters B 748:244-250
Publisher Policy:Reproduced under a Creative Commons License

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