The impact of new polarization data from Bonn, Mainz and Jefferson Laboratory on multipoles

A. V. Anisovich; R. Beck; M. Döring; M. Gottschall; J. Hartmann; V. Kashevarov; E. Klempt; Ulf-G. Meißner; V. Nikonov; M. Ostrick; D. Rönchen; A. Sarantsev; I. Strakovsky; A. Thiel; L. Tiator; U. Thoma; R. Workman; Y. Wunderlich

doi:10.1140/epja/i2016-16284-9

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2023 Impact factor 2.6

Hadrons and Nuclei

Eur. Phys. J. A (2016) 52: 284
https://doi.org/10.1140/epja/i2016-16284-9

Regular Article - Experimental Physics

The impact of new polarization data from Bonn, Mainz and Jefferson Laboratory on $\gamma p \rightarrow \pi N$ multipoles

A. V. Anisovich¹^,2, R. Beck¹^*, M. Döring³^,4, M. Gottschall¹, J. Hartmann¹, V. Kashevarov⁵, E. Klempt¹, Ulf-G. Meißner¹^,6^,7, V. Nikonov¹^,2, M. Ostrick⁵, D. Rönchen¹^,6, A. Sarantsev¹^,2, I. Strakovsky³, A. Thiel¹, L. Tiator⁵, U. Thoma¹, R. Workman³ and Y. Wunderlich¹

¹ Helmholtz-Institut für Strahlen- und Kernphysik der, Universität Bonn, Nußallee 14-16, 53115, Bonn, Germany
² NRS “Kurchatov Institute”, PNPI, 188300, Gatchina, Russia
³ Department of Physics, George Washington University, 725 21st Street, 20052, Washington, DC, USA
⁴ Thomas Jefferson National Accelerator Facility, 12000 Jefferson Avenue, Newport News, VA, USA
⁵ Institut für Kernphysik der Universität Mainz, Johann-Joachim-Becher-Weg 45, 55099, Mainz, Germany
⁶ Bethe Center for Theoretical Physics, Universität Bonn, 53115, Bonn, Germany
⁷ Institut für Kernphysik, Institute for Advanced Simulation, Jülich Center for Hadron Physics, JARA FAME and JARA HPC, Forschungszentrum Jülich, 52425, Jülich, Germany

^* e-mail: beck@hiskp.uni-bonn.de

Received: 21 April 2016
Accepted: 26 July 2016
Published online: 16 September 2016

Abstract

New data on pion-photoproduction off the proton have been included in the partial-wave analyses Bonn-Gatchina and SAID and in the dynamical coupled-channel approach Jülich-Bonn. All reproduce the recent new data well: the double-polarization data for E, G, H, P and T in $\gamma p\rightarrow \pi^{0}p$ from ELSA, the beam asymmetry $\Sigma$ for $\gamma p\rightarrow \pi^{0}p$ and $\pi^{+}n$ from Jefferson Laboratory, and the precise new differential cross section and beam asymmetry data $\Sigma$ for $\gamma p\rightarrow \pi^{0}p$ from MAMI. The new fit results for the multipoles are compared with predictions not taking into account the new data. The mutual agreement is improved considerably but still far from being perfect.