Ab initio study of the photoabsorption of ${}^4$He

Abstract

There are some discrepancies in the low energy data on the photoabsorption cross section of ${}^4$He. We calculate the cross section with realistic nuclear forces and explicitly correlated Gaussian functions. Final state interactions and two- and three-body decay channels are taken into account. The cross section is evaluated in two methods: With the complex scaling method the total absorption cross section is obtained up to the rest energy of a pion, and with the microscopic $R$-matrix method both cross sections ${}^4$He($\gamma ,p$)${}^3$H and ${}^4$He($\gamma ,n$)${}^3$He are calculated below 40\,MeV. Both methods give virtually the same result. The cross section rises sharply from the ${}^3$H+$p$ threshold, reaching a giant resonance peak at 26--27\,MeV. Our calculation reproduces almost all the data above 30\,MeV. We stress the importance of ${}^3$H+$p$ and ${}^3$He+$n$ cluster configurations on the cross section as well as the effect of the one-pion exchange potential on the photonuclear sum rule.

15 pages, 12 figures

References in corpus (6)

• The Lorentz Integral Transform (LIT) method and its applications to perturbation induced reactions
• Global-Vector Representation of the Angular Motion of Few-Particle Systems II
• The ${}^4$He total photo-absorption cross section with two- plus three-nucleon interactions from chiral effective field theory
• Inversion doublets of 3N+N cluster structure in excited states of ${}^4$He
• Photonuclear sum rules and the tetrahedral configuration of ${}^4$He
• A measurement of the 4He(g,n) reaction from 23 < Eg < 70 MeV

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