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2007
Journal Article
Title
Photoproduction of eta-mesons off protons
Abstract
Photoproduction of eta-mesons was studied with the Crystal-Barrel detector at ELSA for photon energies in the range from 0.75 to 3GeV. Total and differential cross-sections are presented. The eta mesons are detected in two decay modes, in eta -> 2gamma and in eta -> 3pi0 -> 6gamma. The cross-sections vary slowly as functions of energy and eta production angle suggesting that only few resonances make significant contributions to the cross-section. For photon energies above 1.5GeV, the differential cross-sections show a strong forward peak due to meson exchanges in the t channel. A comparison of the eta-photoproduction cross-sections with SAID and MAID as well as with a partial-wave analysis performed on our data in combination with other data sets shows good agreement. The Bonn-Gatchina partial-wave analysis suggests that the largest contribution to eta photoproduction for energies below 3GeV proceeds via three resonances, the well-known N(1535)S11, via N(1720)P13, and a suggested N(2070)D15.
Author(s)
Crede, V.
Helmholtz-Institut für Strahlen- und Kernphysik der Universität Bonn, Germany / Department of Physics, Florida State University, Tallahassee, FL, USA
Anisovich, A.V.
Helmholtz-Institut für Strahlen- und Kernphysik der Universität Bonn, Germany / Petersburg Nuclear Physics Institute, Gatchina, Russia
Nikonov, V.A.
Helmholtz-Institut für Strahlen- und Kernphysik der Universität Bonn, Germany / Petersburg Nuclear Physics Institute, Gatchina, Russia
Sarantsev, A.V.
Helmholtz-Institut für Strahlen- und Kernphysik der Universität Bonn, Germany / Petersburg Nuclear Physics Institute, Gatchina, Russia
Thoma, U.
Helmholtz-Institut für Strahlen- und Kernphysik der Universität Bonn, Germany / II. Physikalisches Institut, Universität Giessen, Germany
Walther, D.
Helmholtz-Institut für Strahlen- u. Kernphysik Universität Bonn, Germany / Physikalisches Institut der Universität Bonn, Germany