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تسجيل مستخدم جديدQ^2 Dependence of the S_{11}(1535) Photocoupling and Evidence for a P-wave resonance in eta electroproduction
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New cross sections for the reaction $ep to eeta p$ are reported for total center of mass energy $W$=1.5--2.3 GeV and invariant squared momentum transfer $Q^2$=0.13--3.3 GeV$^2$. This large kinematic range allows extraction of new information about response functions, photocouplings, and $eta N$ coupling strengths of baryon resonances. A sharp structure is seen at $Wsim$ 1.7 GeV. The shape of the differential cross section is indicative of the presence of a $P$-wave resonance that persists to high $Q^2$. Improved values are derived for the photon coupling amplitude for the $S_{11}$(1535) resonance. The new data greatly expands the $Q^2$ range covered and an interpretation of all data with a consistent parameterization is provided.
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The beam-recoil double polarization P_{x}^h and P_{z}^h and the recoil polarization P_{y} were measured for the first time for the p(vec{e},evec{p})eta reaction at a four-momentum transfer of Q^2=0.1 GeV^2/c^2 and a center of mass production angle of
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