A remark on Witten effect for QCD monopoles in matrix quantum mechanics

In a recent work(3) we argued that a certain matrix quantum mechanics may d escribe 't Hooft's monopoles which emerge in QCD when the theory is project ed to its maximal Abelian subgroup. In this letter we find further evidence which supports this interpretation. We study the theory with a nonzero the ta-term. In this case, 't Hooft's QCD monopoles become dyons since they acq uire electric charges due to the Witten effect. We calculate a potential be tween a dyon and an anti-dyon in the matrix quantum mechanics, and find tha t the attractive force between them grows as the theta angle increases.