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 $(\gamma ,2e)$ or $(e,2e)$ angular differential cross sections. Nevertheless, we argue that there are good reasons to believe in the accuracy of the theoretical predictions.

• Received 30 June 1998

DOI:https://doi.org/10.1103/PhysRevLett.81.4588