Scheme transformations in the vicinity of an infrared fixed point

We analyze the effect of scheme transformations in the vicinity of an exact or approximate infrared fixed point in an asymptotically free gauge theory with fermions. We show that there is far less freedom in carrying out such scheme transformations in this case than at an ultraviolet fixed point. We construct a transformation from the MS̄ scheme to a scheme with a vanishing three-loop term in the β function and use this to assess the scheme dependence of an infrared fixed point in SU(N) theories with fermions. Implications for the anomalous dimension of the fermion bilinear operator are also discussed.