Differential cross sections and complete sets of polarization observables are presented for the Gamow-Teller ${}^{12}\mathrm{C}(\overrightarrow{p},\overrightarrow{n}){}^{12}\mathrm{N}(\mathrm{g}.\mathrm{s}.,1^{+})$ reaction at a bombarding energy of 296 MeV with momentum transfers $q$ of 0.1 to $2.2\hspace{0.5em}{\mathrm{fm}}^{-1}$. The polarization transfer observables are used to deduce the spin-longitudinal cross section, ${\mathit{ID}}_q$, and spin-transverse cross sections, ${\mathit{ID}}_p$ and ${\mathit{ID}}_n$. The data are compared with calculations based on the distorted-wave impulse approximation (DWIA) using shell-model wave functions. Significant differences between the experimental and theoretical results are observed for all three spin-dependent ${\mathit{ID}}_i$ at momentum transfers of $q\gtrsim 0.5\hspace{0.5em}{\mathrm{fm}}^{-1}$, suggesting the existence of nuclear correlations beyond the shell model. We also performed DWIA calculations employing random-phase approximation (RPA) response functions and found that the observed discrepancy is partly resolved by the pionic and ρ-mesonic correlation effects.

• Received 24 March 2009

DOI:https://doi.org/10.1103/PhysRevC.80.024319