https://doi.org/10.1140/epja/i2014-14074-1
Regular Article - Experimental Physics
High statistics study of the reaction γp → pπ0 η
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
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.
© SIF, Springer-Verlag Berlin Heidelberg, 2014
