Symmetry of anomalous dimension matrices explained
  In a previous paper, one of us pointed out that the anomalous dimension matrices for all physical processes that have been calculated to date are complex symmetric, if stated in an orthonormal basis. In this paper we prove this fact and show that it is only true in a subset of all possible orthonormal bases, but that this subset is the natural one to use for physical calculations. 
Michael H. Seymour (1 and 2) and Malin Sjodahl (1) ((1) University of   Manchester, (2) CERN)