학술논문
New data on $\vec{\gamma} \vec{p}\rightarrow \eta p$ with polarized photons and protons and their implications for $N^* \to N\eta$ decays
Document Type
Working Paper
Author
Müller, J.; Hartmann, J.; Grüner, M.; Afzal, F.; Anisovich, A. V.; Bantes, B.; Bayadilov, D.; Beck, R.; Becker, M.; Beloglazov, Y.; Berlin, M.; Bichow, M.; Böse, S.; Brinkmann, K. -T.; Challand, T.; Crede, V.; Dietz, F.; Dieterle, M.; Drexler, P.; Dutz, H.; Eberhardt, H.; Elsner, D.; Ewald, R.; Fornet-Ponse, K.; Friedrich, S.; Frommberger, F.; Funke, C.; Gottschall, M.; Gridnev, A.; Goertz, S.; Gutz, E.; Hammann, C.; Hannen, V.; Hannappel, J.; Herick, J.; Hillert, W.; Hoffmeister, P.; Honisch, C.; Jahn, O.; Jude, T.; Jaegle, I.; Käser, A.; Kaiser, D.; Kalinowsky, H.; Kalischewski, F.; Kammer, S.; Keshelashvili, I.; Klassen, P.; Kleber, V.; Klein, F.; Klempt, E.; Koop, K.; Krusche, B.; Kube, M.; Lang, M.; Lopatin, I.; Maghrbi, Y.; Mahlberg, P.; Makonyi, K.; Messi, F.; Metag, V.; Meyer, W.; Müllers, J.; Nanova, M.; Nikonov, V.; Novinski, D.; Novotny, R.; Piontek, D.; Reicherz, G.; Rosenbaum, C.; Rostomyan, T.; Roth, B.; Sarantsev, A.; Schmidt, C.; Schmieden, H.; Schmitz, R.; Seifen, T.; Sokhoyan, V.; Thiel, A.; Thoma, U.; Urban, M.; van Pee, H.; Walther, D.; Wendel, C.; Wiedner, U.; Wilson, A.; Winnebeck, A.; Witthauer, L.; Collaboration, CBELSA/TAPS
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Abstract
The polarization observables $T, E, P, H$, and $G$ in photoproduction of $\eta$ mesons off protons are measured for photon energies from threshold to $W=2400\,$MeV ($T$), 2280 MeV ($E$), 1620 MeV ($P, H$), or 1820 MeV ($G$), covering nearly the full solid angle. The data are compared to predictions from the SAID, MAID, J\"uBo, and BnGa partial-wave analyses. A refit within the BnGa approach including further data yields precise branching ratios for the $N\eta$ decay of nucleon resonances. A $N\eta$-branching ratio of $0.33\pm 0.04$ for $N(1650)1/2^-$ is found, which reduces the large and controversially discussed $N\eta$-branching ratio difference of the two lowest mass $J^P=1/2^-$-resonances significantly.
Comment: 10 pages, 11 figures
Comment: 10 pages, 11 figures