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arXiv · 1604.02922

Double-polarization observable G in neutral-pion photoproduction off the proton

A. Thiel·H. Eberhardt·M. Lang·F. Afzal·A. V. Anisovich·B. Bantes·D. Bayadilov·R. Beck·M. Bichow·K. -T. Brinkmann·S. Böse·V. Crede·M. Dieterle·H. Dutz·D. Elsner·R. Ewald·K. Fornet-Ponse·St. Friedrich·F. Frommberger·Ch. Funke·St. Goertz·M. Gottschall·A. Gridnev·M. Grüner·E. Gutz·D. Hammann·Ch. Hammann·J. Hannappel·J. Hartmann·W. Hillert·Ph. Hoffmeister·Ch. Honisch·T. Jude·D. Kaiser·H. Kalinowsky·F. Kalischewski·S. Kammer·I. Keshelashvili·P. Klassen·V. Kleber·F. Klein·E. Klempt·K. Koop·B. Krusche·M. Kube·I. Lopatin·Ph. Mahlberg·K. Makonyi·V. Metag·W. Meyer·J. Müller·J. Müllers·M. Nanova·V. Nikonov·D. Piontek·S. Reeve·G. Reicherz·S. Runkel·A. Sarantsev·Ch. Schmidt·H. Schmieden·T. Seifen·V. Sokhoyan·K. Spieker·U. Thoma·M. Urban·H. van Pee·D. Walther·Ch. Wendel·A. Wilson·A. Winnebeck·L. Witthauer
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Abstract

This paper reports on a measurement of the double-polarization observable G in $π^0$ photoproduction off the proton using the CBELSA/TAPS experiment at the ELSA accelerator in Bonn. The observable G is determined from reactions of linearly-polarized photons with longitudinally-polarized protons. The polarized photons are produced by bremsstrahlung off a properly oriented diamond radiator. A frozen spin butanol target provides the polarized protons. The data cover the photon energy range from 617 to 1325 MeV and a wide angular range. The experimental results for G are compared to predictions by the Bonn-Gatchina (BnGa), Jülich-Bonn (JüBo), MAID and SAID partial wave analyses. Implications of the new data for the pion photoproduction multipoles are discussed.

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A. Thiel, H. Eberhardt, M. Lang, F. Afzal, A. V. Anisovich, B. Bantes, D. Bayadilov, R. Beck, M. Bichow, K. -T. Brinkmann, S. Böse, V. Crede, M. Dieterle, H. Dutz, D. Elsner, R. Ewald, K. Fornet-Ponse, St. Friedrich, F. Frommberger, Ch. Funke, St. Goertz, M. Gottschall, A. Gridnev, M. Grüner, E. Gutz, D. Hammann, Ch. Hammann, J. Hannappel, J. Hartmann, W. Hillert, Ph. Hoffmeister, Ch. Honisch, T. Jude, D. Kaiser, H. Kalinowsky, F. Kalischewski, S. Kammer, I. Keshelashvili, P. Klassen, V. Kleber, F. Klein, E. Klempt, K. Koop, B. Krusche, M. Kube, I. Lopatin, Ph. Mahlberg, K. Makonyi, V. Metag, W. Meyer, J. Müller, J. Müllers, M. Nanova, V. Nikonov, D. Piontek, S. Reeve, G. Reicherz, S. Runkel, A. Sarantsev, Ch. Schmidt, H. Schmieden, T. Seifen, V. Sokhoyan, K. Spieker, U. Thoma, M. Urban, H. van Pee, D. Walther, Ch. Wendel, A. Wilson, A. Winnebeck, L. Witthauer. 2016-04-11. Double-polarization observable G in neutral-pion photoproduction off the proton. https://doi.org/10.1140/epja%2Fi2017-12194-8

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