High-statistics study of the reaction γp → p2π0

V. Sokhoyan; E. Gutz; V. Crede; 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; B. Metsch; 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; T. Seifen; 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/i2015-15095-x

2021 Impact factor 3.131

Hadrons and Nuclei

This article has an erratum: [https://doi.org/10.1140/epja/i2015-15187-7]

Eur. Phys. J. A (2015) 51: 95
https://doi.org/10.1140/epja/i2015-15095-x

Regular Article - Experimental Physics

High-statistics study of the reaction γp → p2π⁰

The CBELSA/TAPS Collaboration
V. Sokhoyan¹^,a, E. Gutz¹^,2, V. Crede³, 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. Metag², B. Metsch¹, M. Nanova², V. A. Nikonov¹^,4, D. Novinsky¹^,4, R. Novotny², M. Ostrick⁶^,a, L. Pant²^,10, M. Pfeiffer², D. Piontek¹, A. Roy²^,11, A. V. Sarantsev¹^,4, Ch. Schmidt¹, H. Schmieden⁶, T. Seifen¹, S. Shende⁵, A. Süle⁶, V. V. Sumachev⁴, T. Szczepanek¹, A. Thiel¹, U. Thoma¹, D. Trnka², R. Varma²^,11, 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
¹⁰ Nucl. Phys. Div., BARC, Mumbai, India
¹¹ Nucl. Phys. Div., BARC, Mumbai, India

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

Received: 9 June 2015
Revised: 15 July 2015
Accepted: 16 July 2015
Published online: 6 August 2015

Abstract

The photoproduction of 2π ⁰ mesons off protons was studied with the Crystal Barrel/TAPS experiment at the electron accelerator ELSA in Bonn. The energy of photons produced in a radiator was tagged in the energy range from 600 MeV to 2.5 GeV. Differential and total cross sections and pπ ⁰ π ⁰ Dalitz plots are presented. Part of the data was taken with a diamond radiator producing linearly polarized photons, and beam asymmetries were derived. Properties of nucleon and Δ resonances contributing to the pπ ⁰ π ⁰ final state were determined within the Bonn-Gatchina (BnGa) partial-wave analysis. The data presented here allow us to determine branching ratios of nucleon and Δ resonances for their decays into pπ ⁰ π ⁰ via several intermediate states. Most prominent are decays proceeding via Δ(1232)π, N(1440)1/2⁺ π, N(1520)3/2⁻ π, N(1680)5/2⁺ π, but also pf ₀(500), pf ₀(980), and pf ₂(1270) contribute to the reaction.