Meson and Isobar Degrees of Freedom in A($\vec{e},e'\vec{p}$) reactions at $0.2 \leq Q^2 \leq 0.8 (GeV/c)^2$

Abstract

The effect of meson and isobar degrees of freedom in A($\vec{e},e'\vec{p}$) and A(e,e'n) is studied for four-momentum transfers Q^2 in the range between 0.2 and 0.8 (GeV/c)^2. The calculations are performed in a non-relativistic framework with explicit (N,\Delta,\pi) degrees-of-freedom. For the whole range of momentum transfers under investigation the relative effect of the meson-exchange and isobar degrees of freedom is significant. At low missing momenta and quasi-elastic conditions, a tendency to reduce the (e,e'p) and (e,e'n) differential cross sections is noticed. The greatest sensitivity is found in the interference structure functions $W_{LT}$ and $W_{TT}$. The recoil polarization observables, on the other hand, are moderately affected by the meson-exchange and $\Delta$-isobar currents.