Résumé du preprint DAPNIA-07-293

DAPNIA-07-293
Q2 dependence of the S(11)(1535) photocoupling and evidence for a P-wave resonance in eta electroproduction
H. Denizli et al (M. Garçon, F.X. Girod, J.M. Laget, F. Sabatié)
New cross sections for the reaction $ep \\to e\'\\eta p$ 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 $W\\sim$ 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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