Photoproduction of pi0pi0 and pi0pi+-pairs off the proton from threshold to the second resonance region

Abstract

Precise total cross-sections and invariant-mass distributions have been measured for photoproduction of pion pairs off the proton producing $p{\pi }^0{\pi }^0$ and $n{\pi }^{+}{\pi }^0$ final states from the threshold region up to 800 MeV incident photon energy. Additionally, beam helicity asymmetries have been measured in the second resonance region (550 MeV - 820 MeV). The experiment was performed at the tagged photon beam of the Mainz MAMI accelerator with the Crystal Ball and TAPS detectors combined to give an almost 4$\pi$ solid-angle electromagnetic calorimeter. The results are much more precise than any previous measurements and confirm the chiral perturbation theory predictions for the threshold behavior of these reactions. In the second resonance region, the invariant-mass distributions of meson-meson and meson-nucleon pairs are in reasonable agreement with model predictions, but none of the models reproduce the asymmetries for the mixed-charge channel.

accepted for publication in Eur. Phys. J. A

References in corpus (7)

• Ab-initio Determination of Light Hadron Masses
• Study of the gp-->etap reaction with the Crystal Ball detector at the Mainz Microtron(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
• Beam-Helicity Asymmetries in Double Pion Photoproduction off the Proton
• Radiative pi0 photoproduction on protons in the Delta+(1232) region
• Double pion photoproduction off 40Ca

Cited by in corpus (8)

• Light Baryon Spectroscopy
• Photoproduction of pi0-mesons off neutrons in the nucleon resonance region
• 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
• Observation of a structure in the M${}_{p\eta }$ invariant mass distribution near 1700 MeV/$c^2$ in the $\gamma \mathbf{p}\to \mathbf{p}{\pi }^0\eta$ reaction
• Minimal complete sets for two pseudoscalar meson photoproduction
• Helicity-dependent cross sections for the photoproduction of ${\pi }^0$ pairs from nucleons
• Helicity dependent cross sections for the photoproduction of ${\pi }^0{\pi }^{\pm }$ pairs from quasi-free nucleons