Recoil polarization and beam-recoil double polarization measurement of \eta electroproduction on the proton in the region of the S_{11}(1535) resonance

TL;DR

This study measures recoil polarization observables in eta electroproduction on the proton near the S11(1535) resonance, providing new data to test and refine theoretical models of nucleon resonance behavior.

Contribution

First measurement of beam-recoil double polarization observables in eta electroproduction at specific kinematics, offering new insights into resonance dynamics.

Findings

P_{x'}^h and P_{z'}^h agree with phenomenological models

P_{y'} deviates significantly from model predictions

Results help refine understanding of nucleon resonance contributions

Abstract

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},e'\vec{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 \theta = 120^\circ at MAMI C. With a center of mass energy range of 1500 MeV < W < 1550 MeV the region of the S_{11}(1535) and D_{13}(1520) resonance was covered. The results are discussed in the framework of a phenomenological isobar model (Eta-MAID). While P_{x'}^h and P_{z'}^h are in good agreement with the model, P_{y'} shows a significant deviation, consistent with existing photoproduction data on the polarized-target asymmetry.