Neutral pion photoproduction off protons in the energy range 0.3 GeV < E(gamma) < 3 GeV

TL;DR

This study measures differential cross sections for neutral pion photoproduction off protons between 0.3 and 3 GeV, revealing resonance structures and evidence for a new N(2070)D15 resonance.

Contribution

It provides new experimental data on pi0 photoproduction and identifies a potential new resonance, expanding understanding of nucleon resonance spectrum.

Findings

Measured differential cross sections over a wide energy range.

Identified resonance structures in angular distributions.

Evidence for a new resonance N(2070)D15.

Abstract

Single pi0 photoproduction has been studied with the CB-ELSA experiment at Bonn using tagged photon energies between 0.3 and 3.0 GeV. The experimental setup covers a very large solid angle of about 98% of 4 pi. Differential cross sections (d sigma)/(d Omega) have been measured. Complicated structures in the angular distributions indicate a variety of different resonances being produced in the s channel intermediate state gamma p --> N* (Delta*) --> p pi0. A combined analysis including the data presented in this letter along with other data sets reveals contributions from known resonances and evidence for a new resonance N(2070)D15.