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Photoproduction of eta-mesons off protons

: Bartholomy, O.; Bogendörfer, R.; Crede, V.; Fabry, I.; Anisovich, A.V.; Anton, G.; Bantes, B.; Beloglazov, A.; Castelijns, R.; Ehmanns, A.; Ernst, J.; Flemming, H.; Foesel, A.; Fuchs, M.; Funke, C.; Gothe, R.; Gridnev, A.B.; Gutz, E.; Höffgen, Stefan; Horn, I.; Hössl, J.; Junkersfeld, J.; Kalinowsky, H.; Klein, F.; Klempt, E.; Koch, H.; Konrad, M.; Kopf, B.; Krusche, B.; Langheinrich, J.; Löhner, H.; Lopatin, I.V.; Lotz, J.; Matthaey, H.; Menze, D.; Messchendorp, J.G.; Nikonov, V.A.; Novinski, D.V.; Ostrick, M.; Pee, H. van; Radkov, A.; Sarantsev, A.V.; Schadmand, S.; Schmidt, C.; Schmieden, H.; Schoch, B.; Suft, G.; Sumachev, V.; Szczepanek, T.; Thoma, U.; Walther, D.; Weinheimer, C.

Volltext ()

The European physical journal. A, Hadrons and nuclei 33 (2007), Nr.2, S.133-146
ISSN: 1434-6001
ISSN: 1434-601X
ISSN: 1431-5831
Zeitschriftenaufsatz, Elektronische Publikation
Fraunhofer INT ()

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.