Inclusive and exclusive production of eta mesons by pions.

Abstract

Inclusive and exclusive (\ensuremath{\pi},\ensuremath{\eta}) reactions are studied in the framework of a momentum space DWIA model. It is assumed that both reactions are dominated by formation of an N(1535) resonance. Medium corrections for the self-energy of the intermediate ${\mathit{N}}^{\mathrm{*}}$ are taken into account. Cross sections are calculated for (${\mathrm{\ensuremath{\pi}}}^{+}$,\ensuremath{\eta}) inclusive reactions on $^{12}\mathrm{C}$ and compared with experiment and with existing theoretical calculations. We show that quantitative agreement is obtained with experimental data, assuming this reaction is dominated by quasifree single-nucleon knockout, and using an ${\mathit{N}}^{\mathrm{*}}$ free width of 150 MeV. Differential and total cross sections are calculated for the exclusive reaction $^{13}\mathrm{C}$(${\mathrm{\ensuremath{\pi}}}^{+}$,\ensuremath{\eta}${)}^{13}$N.