Helicity-dependent cross sections for the photoproduction of ${\pi }^0$ pairs from nucleons

Abstract

The double-polarization observable $E$ and helicity-dependent cross sections ${\sigma }_{1/2}$, ${\sigma }_{3/2}$ have been measured for the photoproduction of ${\pi }^0$ pairs off quasi-free protons and neutrons at the Mainz MAMI accelerator with the Crystal Ball/TAPS setup. A circularly polarized photon beam was produced by bremsstrahlung from longitudinally polarized electrons and impinged on a longitudinally polarized deuterated butanol target. The reaction products were detected with an almost $4\pi$ covering calorimeter. The results reveal for the first time the helicity- and isospin-dependent structure of the $\gamma N\to N{\pi }^0{\pi }^0$ reaction. They are compared to predictions from reaction models in view of nucleon resonance contributions and also to a refit of one model that predicted results for the proton and for the neutron target. The comparison of the prediction and the refit demonstrate the large impact of the new data.

Submitted to Phys. Rev. Lett

References in corpus (12)

• Upgrade of the Glasgow photon tagging spectrometer for Mainz MAMI-C
• New results on the Roper resonance and the P_{11} partial wave
• Study of the gamma p --> pi0 pi0 p reaction with the Crystal Ball/TAPS at the Mainz
• Photoproduction of pi0pi0 and pi0pi+-pairs off the proton from threshold to the second resonance region
• Beam-Helicity Asymmetries in Double Pion Photoproduction off the Proton
• Production of $\eta$ and ${\eta }^{\prime }$ Mesons on Nucleons and Nuclei
• Insight into the narrow structure in {\boldmath{$\eta$}}-photoproduction on the neutron from helicity dependent cross sections
• Photoproduction of pi0-mesons off neutrons in the nucleon resonance region
• First measurement of the polarization observable $E$ and helicity-dependent cross sections in single ${\pi }^0$ photoproduction from quasi-free nucleons
• Measurement of the beam-helicity asymmetry $I^{\odot }$ in the photoproduction of ${\pi }^0{\pi }^{\pm }$-pairs off protons and off neutrons
• Photoproduction ofeta-pi pairs off nucleons and deuterons
• Polarization observables in ${\pi }^0\eta$-photoproduction on the proton

Cited by in corpus (4)

• Light Baryon Spectroscopy
• Minimal complete sets for two pseudoscalar meson photoproduction
• Helicity dependent cross sections for the photoproduction of ${\pi }^0{\pi }^{\pm }$ pairs from quasi-free nucleons
• Possible manifestation of the 2p pionium in particle physics processes