Strong Cancellations of Neutron and Proton Transition Amplitudes Observed in Pion Inelastic Scattering fromC14

Differential cross sections were measured for inelastic scattering of 164-MeV ${\pi }^{+}$ and ${\pi }^{-}$ from ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$. Large cross-section ratios, $R=\frac{\sigma \left({\pi }^{+}\right)}{\sigma \left({\pi }^{-}\right)}$ (or $R^{-1\mathrm{}}$), were observed, two being significantly larger than the free $\pi$-nucleon value. Lower limits are $R>\mathrm{}26\mathrm{}$, $R^{-1\mathrm{}}>17\mathrm{}$, and $R>\mathrm{}11\mathrm{}$ for states at 8.32 MeV ($2^{+}$), 11.67 MeV ($4^{-}$), and 17.26 MeV ($4^{-}$), respectively. These values are interpreted as being due to strong cancellations of the neutron and proton components of the transition amplitudes.