Calculation of circular dichroism in helium double photoionization

We apply the convergent close-coupling (CCC) method to the calculation of the circular dichroism in helium double photoionization for a photon energy of 99 eV. Comparison is made with the measurements of Mergel et al. [Phys. Rev. Lett. 80, 5301 (1998)], and substantial discrepancy is found. This is the first example where the CCC theory yields such disagreement with experiment for either (γ, 2e) or (e, 2e) angular differential cross sections. Nevertheless, we argue that there are good reasons to believe in the accuracy of the theoretical predictions.