A bstract We calculate the two-mass three-loop contributions to the unpolarized and polarized massive operator matrix elements Aₐ₆^ (3) and Aₐ₆^ (3) in x -space for a general mass ratio by using a semi-analytic approach. We also compute Mellin moments up to N = 2000 (3000) by an independent method, to which we compare the results in x -space. In the polarized case, we work in the Larin scheme. We present numerical results. The two-mass contributions amount to about 50% of the full O (T₅^2) and O (T₅^3) terms contributing to the operator matrix elements. The present result completes the calculation of all unpolarized and polarized massive three-loop operator matrix elements.
Ablinger et al. (Fri,) studied this question.