Excitation of Abnormal Parity States byαParticles Acting with Velocity-Dependent Central Forces

The violation of the normal parity rule in ($\alpha ,{\alpha }^{\prime }$) scattering is related to a velocity dependence in a purely central, spin-independent $\alpha -N$ force. The distorted-wave Born-approximation formalism of the process is presented, and the specific case of the $3^{+}$ state in ${\mathrm{Ni}}^{58}$ is calculated in the plane-wave Born approximation. The role of the velocity dependence is discussed in physical terms, and a formal similarity with Weber's old theory of electromagnetism is found.