Key points are not available for this paper at this time.
We investigate the perturbative ambiguity of the radiatively induced Chern-Simons term in differential regularization. The result obtained by this method contains all those obtained by other regularization schemes and the ambiguity is explicitly characterized by an indefinite ratio of two renormalization scales. It is argued that the ambiguity can only be eliminated by either imposing a physical requirement or resorting to a more fundamental principle. Some calculation techniques in coordinate space are developed in the appendixes.
W. F. Chen (Mon,) studied this question.