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.

arXiv commentSubmitted to Phys. Rev. Lett

References in corpus (28)

• Completeness Rules for Spin Observables in Pseudoscalar Meson Photoproduction
• Study of Non-Strange Baryon Resonances with Meson Photoproduction
• Upgrade of the Glasgow photon tagging spectrometer for Mainz MAMI-C
• Double Pion Photoproduction on the Nucleon: Study of the Isospin Channels
• New results on the Roper resonance and the P_{11} partial wave
• Double pion photoproduction on nucleon and deuteron
• High statistics study of the reaction $\gamma p\to p{\pi }^0\eta$
• Polarization Observables for Two-Pion Production off the Nucleon
• N* and Delta* decays into N pi0 pi0
• High statistics study of the reaction $\gamma p\to p2{\pi }^0$
• Photoproduction of mesons off nuclei
• 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
• Double ${\pi }^0$ Photoproduction off the Proton at Threshold
• Insight into the narrow structure in {\boldmath{$\eta$}}-photoproduction on the neutron from helicity dependent cross sections
• Production of $\eta$ and ${\eta }^{\prime }$ Mesons on Nucleons and Nuclei
• Measurement of the beam-helicity asymmetry $I^{\odot }$ in the photoproduction of ${\pi }^0$-pairs off the proton and off the neutron
• Photoproduction of pi0-mesons off neutrons in the nucleon resonance region
• Helicity-dependent cross sections and double-polarization observable E in eta photoproduction from quasi-free protons and neutrons
• 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
• Study of the $\gamma p\to {\pi }^0\eta p$ reaction with the A2 setup at MAMI
• Photoproduction ofeta-pi pairs off nucleons and deuterons
• Polarization observables in ${\pi }^0\eta$-photoproduction on the proton
• Photoproduction of {\boldmath{${\pi }^0$}} Mesons off Protons and Neutrons in the Second and Third Nucleon Resonance Region
• First measurement of helicity-dependent cross sections in pi0-eta photoproduction from quasi-free nucleons
• Theory of two-pion photo- and electroproduction off the nucleon

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