High statistics study of the reaction γp → pπ0 η

E. Gutz; V. Crede; V. Sokhoyan; H. van Pee; A. V. Anisovich; J. C. S. Bacelar; B. Bantes; O. Bartholomy; D. Bayadilov; R. Beck; Y. A. Beloglazov; R. Castelijns; H. Dutz; D. Elsner; R. Ewald; F. Frommberger; M. Fuchs; Ch. Funke; R. Gregor; A. B. Gridnev; W. Hillert; Ph. Hoffmeister; I. Horn; I. Jaegle; J. Junkersfeld; H. Kalinowsky; S. Kammer; V. Kleber; Frank Klein; Friedrich Klein; E. Klempt; M. Kotulla; B. Krusche; M. Lang; H. Löhner; I. V. Lopatin; S. Lugert; T. Mertens; J. G. Messchendorp; V. Metag; M. Nanova; V. A. Nikonov; D. Novinsky; R. Novotny; M. Ostrick; L. Pant; M. Pfeiffer; D. Piontek; A. Roy; A. V. Sarantsev; Ch. Schmidt; H. Schmieden; S. Shende; A. Süle; V. V. Sumachev; T. Szczepanek; A. Thiel; U. Thoma; D. Trnka; R. Varma; D. Walther; Ch. Wendel; A. Wilson

doi:10.1140/epja/i2014-14074-1

2021 Impact factor 3.131

Hadrons and Nuclei

Eur. Phys. J. A (2014) 50: 74
https://doi.org/10.1140/epja/i2014-14074-1

Regular Article - Experimental Physics

High statistics study of the reaction γp → pπ⁰ η

The CBELSA/TAPS Collaboration
E. Gutz¹^,2, V. Crede³, V. Sokhoyan¹^,a, H. van Pee¹, A. V. Anisovich¹^,4, J. C. S. Bacelar⁵, B. Bantes⁶, O. Bartholomy¹, D. Bayadilov¹^,4, R. Beck¹, Y. A. Beloglazov⁴, R. Castelijns⁵, H. Dutz⁶, D. Elsner⁶, R. Ewald⁶, F. Frommberger⁶, M. Fuchs¹, Ch. Funke¹, R. Gregor², A. B. Gridnev⁴, W. Hillert⁶, Ph. Hoffmeister¹, I. Horn¹, I. Jaegle⁷, J. Junkersfeld¹, H. Kalinowsky¹, S. Kammer⁶, V. Kleber⁶^,b, Frank Klein⁶, Friedrich Klein⁶, E. Klempt¹^*, M. Kotulla²^,7, B. Krusche⁷, M. Lang¹, H. Löhner⁵, I. V. Lopatin⁴, S. Lugert², T. Mertens⁷, J. G. Messchendorp⁵, V. Metag³, M. Nanova³, V. A. Nikonov¹^,4, D. Novinsky¹^,4, R. Novotny², M. Ostrick⁶^,a, L. Pant²^,d, M. Pfeiffer², D. Piontek¹, A. Roy²^,e, A. V. Sarantsev¹^,4, Ch. Schmidt¹, H. Schmieden⁶, S. Shende⁵, A. Süle⁶^,e, V. V. Sumachev⁴, T. Szczepanek¹, A. Thiel¹, U. Thoma¹, D. Trnka², R. Varma²^,e, D. Walther¹^,6, Ch. Wendel¹ and A. Wilson¹^,3

¹ Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn, Bonn, Germany
² II. Physikalisches Institut, Universität Gießen, Gießen, Germany
³ Department of Physics, Florida State University, Tallahassee, USA
⁴ Petersburg Nuclear Physics Institute, Gatchina, Russia
⁵ Kernfysisch Versneller Instituut, Groningen, The Netherlands
⁶ Physikalisches Institut, Universität Bonn, Bonn, Germany
⁷ Institut für Physik, Universität Basel, Basel, Switzerland

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

Received: 12 February 2014
Revised: 12 March 2014
Accepted: 24 March 2014
Published online: 17 April 2014

Abstract

Photoproduction off protons of the pπ ⁰ η three-body final state was studied with the Crystal Barrel/TAPS detector, at the electron stretcher accelerator ELSA in Bonn, for incident energies from the π ⁰ η production threshold up to 2.5 GeV. Differential cross sections and the total cross sections are presented. The use of linearly polarized photons gives access to the polarization observables Σ, I ^s, and I ^c, the latter two characterize beam asymmetries in case of three-body final states. Δ(1232)η, N(1535)1/2⁻ π, and pa ₀(980) are the dominant isobars contributing to the reaction. The partial wave analysis confirms the existence of some nucleon and Δ resonances, for which so far only fair evidence was reported. A large number of decay modes of known nucleon and Δ resonances is presented. It is shown that detailed investigations of decay branching ratios may provide a key to unravelling the structure of nucleon and Δ resonances.