Measurement of the Recoil Polarization in the $\mathit{p}(\overrightarrow{e},{\mathit{e}}^{\prime }\overrightarrow{p}){\mathit{\pi }}^0$ Reaction at the $\mathit{\Delta }\left(1232\right)$ Resonance

The recoil proton polarization has been measured in the $p\left(\overrightarrow{e}{,e}^{\prime }\overrightarrow{p}\right){\pi }^0$ reaction in parallel kinematics around $W=1232\mathrm{MeV}$, $Q^2=0.121(\mathrm{GeV}/c{)}^2$, and $\epsilon =0.718\mathrm{}$ using the polarized cw electron beam of the Mainz Microtron. All three proton polarization components, $P_x/P_e=(-11.4\mathrm{}\pm 1.3\pm 1.4)\%$, $P_y=(-43.1\mathrm{}\pm 1.3\pm 2.2)\%$, and $P_z/P_e=(56.2\pm 1.5\pm 2.6)\%$, could be measured simultaneously. The Coulomb quadrupole to magnetic dipole ratio, $\mathrm{CMR}=(-6.4\mathrm{}\pm {0.7}_{\mathrm{stat}}\pm {0.8}_{\mathrm{syst}})\%$, was determined from $P_x$ in the framework of the Mainz Unitary Isobar Model. The consistency among the reduced polarizations and the extraction of the ratio of longitudinal-to-transverse response is discussed.