Double-polarization observable G in neutral-pion photoproduction off the proton The CBELSA/TAPS Collaboration, A. Thiel, H. Eberhardt, M. Lang, F. Afzal, A. V. Anisovich, B. Bantes, D. Bayadilov, R. Beck, M. Bichow et al. (63 more) Eur. Phys. J. A, 53 1 (2017) 8 Published online: 18 January 2017 DOI: 10.1140/epja/i2017-12194-8