0000000000585514
AUTHOR
Michio Kohno
Proton distortion effects and meson exchange current contributions in the (e,e′p) reaction
It is demonstrated that proton distortion effects could explain the relative enhancement of transverse to longitudinal response in the recent ($e,{e}^{\ensuremath{'}}p$) reactions on $^{12}\mathrm{C}$. The spin-orbit field is essential to bring about this enhancement. The role of the convection current is pointed out. Favorable contributions from pion-pair and isobar-excitation currents are also found.
Pion-induced η production on nuclei
Abstract Low-energy η production on nuclei is investigated in a DWIA framework, using a Green function method. The η potential is constructed by folding medium-modified η N → S 11 → η N scattering amplitudes with nuclear wave functions. A phenomenological spreading potential is introduced for the intermediate S 11 resonance. Calculated ( π + , p ) η cross sections on 12 C and 16 O with the spreading potential having an imaginary part of the order of −50 ∼ −100 MeV compare favorably with recent experimental data. It is also shown that the energy dependence of the ( π + , η ) inclusive spectra is nicely reproduced, though the magnitude is somewhat underestimated.