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

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Cited by in corpus (56)

• Baryon spectroscopy
• Properties of baryon resonances from a multichannel partial wave analysis
• Progress Toward Understanding Baryon Resonances
• Photoproduction of $\eta$ and $\eta \prime$ Mesons off Protons
• Measurement of eta photoproduction on the proton from threshold to 1500 MeV
• Eta photoproduction in a combined analysis of pion- and photon-induced reactions
• Quasi-free photoproduction of eta-mesons of the neutron
• Eta-meson production in the resonance energy region
• Determination of the η'-nucleus optical potential
• Anomaly in the K^0_S Sigma^+ photoproduction cross section off the proton at the K* threshold
• On the cross section ratio sigma_n/sigma_p in eta photoproduction
• Quasi-free photoproduction of eta-mesons off the deuteron
• Quasifree photoproduction of $\eta$ mesons off protons and neutrons
• Light Baryon Spectroscopy
• Linearly polarised photon beams at ELSA and measurement of the beam asymmetry in pi^0-photoproduction off the proton
• Photoproduction Reactions and Non-Strange Baryon Spectroscopy
• Photoproduction of pions and properties of baryon resonances from a Bonn-Gatchina partial wave analysis
• Photoproduction of mesons off nuclei
• K^0 pi^0 Sigma^+ and K^*0 Sigma^+ photoproduction off the proton
• Photoproduction of eta meson within a coupled-channels K-matrix approach
• In-medium $\omega$ mass from the $\gamma +Nb\to {\pi }^0\gamma +X$ reaction
• Measurement of the transverse target and beam-target asymmetries in $\eta$ meson photoproduction at MAMI
• Pion- and photo-induced transition amplitudes to $\Lambda K$, $\Sigma K$, and $N\eta$
• Photon beam asymmetry $\Sigma$ for $\eta$ and ${\eta }^{\prime }$ photoproduction from the proton
• Photoproduction of meson pairs: First measurement of the polarization observable I^s
• Photoproduction of ω Mesons off the Proton
• Photoproduction of ${\eta }^{\prime }$-mesons off the deuteron
• 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
• Singularity structure of the pi N scattering amplitude in a meson-exchange model up to energies W < 2.0 GeV
• Measurement of the Beam Asymmetry $\Sigma$ in the Forward Direction for pi0 Photoproduction
• Quasi-free photoproduction of eta-mesons off 3He nuclei
• Beam asymmetry in near threshold omega photoproduction off the proton
• Combined study of gamma p to eta p and pi-p to eta n in a chiral constituent quark approach
• Beam Asymmetry $\mathbf{\Sigma }$ for the Photoproduction of $\eta$ and ${\eta }^{\prime }$ Mesons at ${\mathbf{E}}_{\gamma }=8.8$GeV
• Helicity-dependent cross sections and double-polarization observable E in eta photoproduction from quasi-free protons and neutrons
• $\eta$ production off the proton in a Regge-plus-chiral quark approach
• Mass splittings of SU(3) baryons within a chiral soliton model
• Photoproduction of eta mesons from the neutron: cross sections and double polarization observable E
• 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
• Measurement of polarisation observables in $K_s^0{\Sigma }^{+}$ photoproduction off the proton
• Chiral constituent quark model study of the process $\gamma p\to \eta p$
• Toward a unified description of hadro- and photoproduction: S-wave pi- and eta-photoproduction amplitudes
• Differential cross section and photon-beam asymmetry for the gamma p -> pi- Delta++(1232) reaction at forward pi- angles for Egamma=1.5-2.95 GeV
• Partial-wave analyses of $\gamma p\to \eta p$ \ and $\gamma n\to \eta n$ using a multichannel framework
• 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
• Mass splittings of the baryon decuplet and antidecuplet with the second-order flavor symmetry breakings within a chiral soliton model
• In-medium Properties of η' Meson
• Polarization observables in double neutral pion photoproduction
• Physics at ELSA
• Beam Asymmetries ($\Sigma$) for ${\pi }^0$, $\eta$ and ${\eta }^{\prime }$ in Photoproduction at GlueX
• Exploration of hyperfine interaction between constituent quarks via eta productions