Implications of spin-current couplings forP±Ain inelastic proton scattering

Abstract

Nonlocal spin-dependent couplings in the effective nucleon-nucleon interaction are shown to probe current $\ensuremath{\bigotimes}$ spin correlations in inelastic nuclear excitations. Together, these couplings and correlations provide an important dynamical source of polarization-analyzing-power differences observed in inelastic proton scattering. This is illustrated explicitly by schematic calculations for ${0}^{+}\ensuremath{\rightarrow}{1}^{+}$ and ${0}^{+}\ensuremath{\rightarrow}{0}^{\ensuremath{-}}$ transitions. More realistic distorted-wave impulse approximation calculations have been made for the ${0}^{+}\ensuremath{\rightarrow}{1}^{+}$ transition in $^{90}\mathrm{Zr}$ at ${E}_{x}=8.9$ MeV which support the more transparent schematic considerations. Distorted-wave impulse approximation calculations are also compared with experimental (p,p') data for the two lowest ${1}^{+}$ excitations in $^{12}\mathrm{C}$. For isovector ${0}^{+}\ensuremath{\rightarrow}{1}^{+}$ transitions these nuclear structure spin $\ensuremath{\bigotimes}$ current correlations also enter $\ensuremath{\beta}$ decay through the "induced tensor" couplings, and this relationship is used to help identify the nonlocality in the nucleon-nucleon effective interaction.