Measurement of the beam asymmetry in eta-photoproduction off the proton

Abstract

The beam asymmetry, $\Sigma$, was measured at ELSA in the reaction $\vec{\gamma }p\to \eta p$ using linearly polarised tagged photon beams, produced by coherent bremsstrahlung off a diamond. The crystal was oriented to provide polarised photons in the energy range $E_{\gamma }=800$ to 1400 MeV with the maximum polarisation of $P_{\gamma }=49$ % obtained at 1305 MeV. Both dominant decay modes of the $\eta$ into two photons and $3{\pi }^0$ were used to extract the beam asymmetry from the azimuthal modulation of the cross section. The measurements cover the angular range ${\Theta }_{\text{cm}}\simeq 50$ -- 150 degrees. Large asymmetries up to 80 % are observed, in agreement with a previous measurement. The eta-MAID model and the Bonn--Gatchina partial wave analysis describe the measurements, but the required partial waves differ significantly.

8 pages, 8 figures, submitted to EPJA

Cited by in corpus (21)

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• Study of $\eta$ photoproduction on the proton in a chiral constituent quark approach via one-gluon-exchange model
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• Singularity structure of the pi N scattering amplitude in a meson-exchange model up to energies W < 2.0 GeV
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• Axial-vector transitions and strong decays of the baryon antidecuplet in the self-consistent SU(3) chiral quark-soliton model
• Vector transition form factors of the $N{K}^{\ast }\to {\Theta }^{+}$ and $N{\bar{K}}^{\ast }\to {\Sigma }_{\overline{10}}^{\ast -}$ in the SU(3) chiral quark-soliton model
• Chiral constituent quark model study of the process $\gamma p\to \eta p$
• Measurement of polarisation observables in $K_s^0{\Sigma }^{+}$ photoproduction off the proton
• Energy dependent analysis of eta-meson photoproduction on protons and neutrons without background in the energy region up to 3.4 GeV
• Photoproduction of $\eta$ mesons off the proton for $1.2<E_{\gamma }<4.7$ GeV using CLAS at Jefferson Laboratory
• Investigation of the anomaly in eta-photoproduction off the neutron
• Configuration Mixing of Quark States in Baryons
• Polarization observables in double neutral pion photoproduction