Integrated Photodisintegration Cross Section of Helium with a Velocity-Dependent Nuclear Potential

We calculate the integrated cross section ${\sigma }_{\mathrm{int}}$ for the photodisintegration of helium (${\mathrm{He}}^4$) by applying the sum rules of Levinger and Bethe and using Irving's wave function. We assume the two-body interaction to be central and velocity-dependent both in ${}_{}{}^1{}_{}{}^{}S$ and ${}_{}{}^3{}_{}{}^{}S$ states. Our value for ${\sigma }_{\mathrm{int}}$ agrees reasonably well with the experimental results of Gorbunov and Spiridonov and with the theoretical value of Goldhammer and Valk obtained by using hard-core wave functions and potentials. Moreover, we find, in good agreement with Dohnert and Rojo, that the velocity-dependent potential increases the value of ${\sigma }_{\mathrm{int}}$ by about 17% over the values obtained with a purely central potential.