https://doi.org/10.1140/epja/i2015-15095-x
Regular Article - Experimental Physics
High-statistics study of the reaction γp → p2π0
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
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.
© SIF, Springer-Verlag Berlin Heidelberg, 2015