Photon asymmetry measurements of $$\overrightarrow{\gamma}p \rightarrow \pi^{0} p$$ γ → p → π 0 p for $$E_{\gamma}=$$ 320-650 MeV

Journal Article · 16 November 2016 · European Physical Journal. A

DOI: https://doi.org/10.1140/epja/i2016-16333-5 · OSTI ID:1425737

Gardner, S. ^[1]; Howdle, D.; Sikora, M. H.; Wunderlich, Y.; Abt, S.; Achenbach, P.; Afzal, F.; Aguar-Bartolome, P.; Ahmed, Z.; Annand, J. R. M.; Arends, H. J.; Bantawa, K.; Bashkanov, M.; Beck, R.; Biroth, M.; Borisov, N. S.; Braghieri, A.; Briscoe, W. J.; Cherepnya, S.; Cividini, F. ; Costanza, S.; Collicott, C.; Demissie, B. T.; Denig, A.; Dieterle, M.; Downie, E. J.; Drexler, P.; Ferretti-Bondy, M. I.; Filkov, L. V.; Glazier, D. I.; Garni, S.; Gradl, W.; Günther, M.; Gurevich, G. M.; Hall Barrientos, P.; Hamilton, D.; Heid, E.; Hornidge, D.; Huber, G. M.; Jahn, O.; Jude, T. C.; Käser, A.; Kay, S.; Kashevarov, V. L.; Keshelashvili, I.; Kondratiev, R.; Korolija, M.; Krusche, B.; Linturi, J. M.; Lisin, V.; Livingston, K.; Lutterer, S.; MacGregor, I. J. D.; Macrae, R.; Mancell, J.; Manley, D. M.; Martel, P. P.; McGeorge, J. C.; McNicoll, E. F.; Middleton, D. G.; Miskimen, R.; Mullen, C.; Mushkarenkov, A.; Neganov, A. B.; Neiser, A.; Nikolaev, A.; Oberle, M.; Ostrick, M.; Owens, R. O.; Otte, P. B.; Oussena, B.; Paudyal, D.; Pedroni, P.; Polonski, A.; Prakhov, S.; Rajabi, A.; Robinson, J.; Rosner, G.; Rostomyan, T.; Sarty, A.; Schumann, S.; Sokhoyan, V.; Spieker, K.; Steffen, O.; Sfienti, C.; Strakovsky, I. I.; Strandberg, B.; Strub, Th.; Supek, I.; Tarbert, C. M.; Thiel, A.; Thiel, M.; Thomas, A.; Unverzagt, M.; Usov, Yu. A.; Watts, D. P.; Werthmüller, D.; Wettig, J.; Wolfes, M.; Witthauer, L.; Zana, L.

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1. SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK

High-statistics measurements of the photon asymmetry Σ for the $$\overrightarrow{\gamma}p \rightarrow \pi^{0} p$$ reaction have been made in the center-of-mass energy range W = 1214–1450 MeV. The data were measured with the MAMI A2 real photon beam and Crystal Ball/TAPS detector systems in Mainz, Germany. The resulting measurements significantly improve the existing world data and are shown to be in good agreement with previous measurements, and with the MAID, SAID, and Bonn-Gatchina predictions. We have also combined the photon asymmetry results with recent cross-section measurements from Mainz to calculate the profile functions, $$\check{Σ}$$ (= σ₀Σ), and perform a moment analysis. Comparison with calculations from the Bonn-Gatchina model shows that the precision of the data is good enough to further constrain the higher partial waves, and there is an indication of interference between the very small F-waves and the N(1520)3/2^- and N(1535)1/2^- resonances.

• Research Organization: George Washington Univ., Washington, DC (United States)
• Sponsoring Organization: European Union (EU); German Research Foundation (DFG); National Science Foundation (NSF); Natural Sciences and Engineering Research Council of Canada (NSERC); Science and Technology Facilities Council (STFC) (United Kingdom); Swiss National Science Foundation (SNSF); USDOE
• Contributing Organization: The A2 Collaboration at MAMI
• Grant/Contract Number: SC0014133
• OSTI ID: 1425737
• Journal Information: European Physical Journal. A, Journal Name: European Physical Journal. A Journal Issue: 11 Vol. 52; ISSN 1434-6001
• Publisher: SpringerCopyright Statement
• Country of Publication: United States
• Language: English