6533b7d6fe1ef96bd12663f0

RESEARCH PRODUCT

Determination of theE2/M1ratio in theγN→Δ(1232)transition from a simultaneous measurement ofp(γ→,p)π0andp(γ→,π+)n

subject

description

Tagged linearly polarized photons have been used at the Mainz Microtron (MAMI) for simultaneous measurements of the $p(\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\gamma}},p){\ensuremath{\pi}}^{0}$ and $p(\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\gamma}},{\ensuremath{\pi}}^{+})n$ reaction channels to study the $\ensuremath{\gamma}\stackrel{\ensuremath{\rightarrow}}{N}\ensuremath{\Delta}(1232)$ transition. The energy dependence of the magnetic dipole ${M}_{1+}^{3/2}$ and electric quadrupole ${E}_{1+}^{3/2}$ amplitudes have been extracted from these data in the photon energy range from $270$ to 420 MeV. The $E2/M1$ ratio for the $\ensuremath{\gamma}\stackrel{\ensuremath{\rightarrow}}{N}\ensuremath{\Delta}(1232)$ transition has been determined to be $\ensuremath{-}(2.5\ifmmode\pm\else\textpm\fi{}{0.1}_{\mathrm{stat}}\ifmmode\pm\else\textpm\fi{}{0.2}_{\mathrm{sys}})%$ at the resonance position $({\ensuremath{\delta}}_{33}=90\ifmmode^\circ\else\textdegree\fi{}).$