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First measurement of the helicity asymmetry for $\gamma p\rightarrow p\pi^0$ in the resonance region

Authors :
Gottschall, M.
Anisovich, A. V.
Bantes, B.
Bayadilov, D.
Beck, R.
Bichow, M.
Böse, S.
Brinkmann, K. -Th.
Challand, Th.
Crede, V.
Dietz, F.
Dutz, H.
Eberhardt, H.
Elsner, D.
Ewald, R.
Fornet-Ponse, K.
Friedrich, St.
Frommberger, F.
Funke, Ch.
Gridnev, A.
Grüner, M.
Gutz, E.
Hammann, Ch.
Hannappel, J.
Hartmann, J.
Hillert, W.
Hoffmeister, Ph.
Honisch, Ch.
Jaegle, I.
Kaiser, D.
Kalinowsky, H.
Kammer, S.
Keshelashvili, I.
Klein, F.
Klempt, E.
Koop, K.
Krusche, B.
Kube, M.
Lang, M.
Lopatin, I.
Maghrbi, Y.
Makonyi, K.
Metag, V.
Meyer, W.
Müller, J.
Nanova, M.
Nikonov, V.
Novotny, R.
Piontek, D.
Reicherz, G.
Rostomyan, T.
Sarantsev, A.
Schaepe, St.
Schmidt, Ch.
Schmieden, H.
Schmitz, R.
Seifen, T.
Sokhoyan, V.
Thiel, A.
Thoma, U.
Urban, M.
van Pee, H.
Walther, D.
Wendel, Ch.
Wiedner, U.
Wilson, A.
Winnebeck, A.
Source :
M. Gottschall et al., Phys. Rev. Lett. 112, 012003 (2014)
Publication Year :
2013

Abstract

The first measurement of the helicity dependence of the photoproduction cross section of single neutral pions off protons is reported for photon energies from 600 to 2300\,MeV, covering nearly the full solid angle. The data are compared to predictions from the SAID, MAID, and BnGa partial wave analyses. Strikingly large differences between data and predictions are observed which are traced to differences in the helicity amplitudes of well known and established resonances. Precise values for the helicity amplitudes of several resonances are reported.

Subjects

Subjects :
Nuclear Experiment

Details

Database :
arXiv
Journal :
M. Gottschall et al., Phys. Rev. Lett. 112, 012003 (2014)
Publication Type :
Report
Accession number :
edsarx.1312.2187
Document Type :
Working Paper
Full Text :
https://doi.org/10.1103/PhysRevLett.112.012003
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