Antinucleon as a probe of nuclear spin and isospin excitations

Using two models for the antinucleon-nucleon ($\overline{\mathrm{N}}\mathrm{N}$) interaction, we obtain complex, energy dependent $\overline{\mathrm{N}}\mathrm{N}$ transition operators $t$ appropriate for ($\overline{\mathrm{N}}, {\overline{\mathrm{N}}}^{\prime }$) inelastic scattering studies on complex nuclei. It is shown that the spin-isospin dependence of the $\overline{\mathrm{N}}\mathrm{N}$ annihilation potential plays an important role in determining the dominant spin-isospin modes in the nuclear response. In particular, for the most realistic of our $\overline{\mathrm{N}}\mathrm{N}$ models, a large spin dependent component $t_{\sigma }$ is obtained, leading to the strong excitation of isoscalar spin-flip states; this term is suppressed in the corresponding NN $t$ matrix. The central spin and isospin independent term, $t_0^c$, is large for $\overline{\mathrm{N}}\mathrm{N}$, at all relevant momentum transfers $q$. At high $q$ the isoscalar spin-orbit ($t_0^{\mathrm{LS}}$) and isovector tensor ($t_{\tau }^T$) components are important. Cross section and analyzing power predictions for $\overline{\mathrm{N}}$ inelastic scattering as well as corrections due to energy and density dependence are discussed.