Brueckner--Goldstone many-body perturbation calculation of helium photoionization

A calculation is carried out within the framework of the Brueckner-Goldstone many-body perturbation approach for the photoionization of helium. In particular, we have utilized a newly developed technique of multiple basis sets to circumvent the difficulty of evaluating the singular integrals which appear in the important final-state correlation. This technique also enables us to achieve considerable calculational simplicity, reducing the final evaluation to only two diagrams. Our result agrees well with the accurate experimental data of Samson.