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 (7)

• Measurement of eta photoproduction on the proton from threshold to 1500 MeV
• Quasi-free photoproduction of eta-mesons of the neutron
• Linearly polarised photon beams at ELSA and measurement of the beam asymmetry in pi^0-photoproduction off the proton
• Study of $\eta$ photoproduction on the proton in a chiral constituent quark approach via one-gluon-exchange model
• Photoproduction of eta-mesons off nuclei for Eg < 2.2 GeV
• 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 $\gamma p\to \eta p$