Eur. Phys. J. A (2007) 34: 49-68
https://doi.org/10.1140/epja/i2007-10482-6

Regular Article - Theoretical Physics

Regge approach to charged pion photoproduction at invariant energies above 2 GeV

¹ Excited Baryon Analysis Center (EBAC), Thomas Jefferson National Accelerator Facility, 23606, Newport News, VA, USA
² Helmholtz-Institut für Strahlen- und Kernphysik (Theorie), Universität Bonn, Nußallee 14-16, D-53115, Bonn, Germany
³ Institut für Kernphysik (Theorie), Forschungszentrum Jülich, D-52425, Jülich, Germany
⁴ Physics Division, Argonne National Laboratory, 60439, Argonne, IL, USA
⁵ Theory Center, Thomas Jefferson National Accelerator Facility, 12000 Jefferson Ave., 23606, Newport News, VA, USA
⁶ College of William and Mary, 23187, Williamsburg, VA, USA

^* e-mail: j.haidenbauer@fz-juelich.de

Received: 31 May 2007
Accepted: 10 September 2007
Published online: 11 October 2007

Abstract

A Regge model with absorptive corrections is employed in a global analysis of the world data on positive and negative pion photoproduction for photon energies from 3 to 8GeV. In this region resonance contributions are expected to be negligible so that the available experimental information on differential cross-sections and single polarization observables at - t ⩽ 2 GeV^2 allows us to determine the non-resonant part of the reaction amplitude reliably. The model amplitude is then used to predict observables for photon energies below 3GeV. Differences between our predictions and data in this energy region are systematically examined as possible signals for the presence of excited baryons. We find that the data available for the polarized photon asymmetry show promising resonance signatures at invariant energies around 2GeV. With regard to differential cross-sections the analysis of negative pion photoproduction data, obtained recently at JLab, indicates likewise the presence of resonance structures around 2GeV.