New Scheme Transformations and Application to Study Scheme Dependence of   an Infrared Zero of the Beta Function in Gauge Theories
  We present two new one-parameter families of scheme transformations and apply these to study the scheme dependence of the infrared zero in the beta function of an asymptotically free non-Abelian gauge theory up to four-loop order. Our results provide a further quantitative measure of this scheme dependence, showing that for moderate values of the gauge coupling and the parameter specifying the scheme transformation, this dependence is relatively mild. We also remark on a generalized multi-parameter family of rational scheme transformations. 
Gongjun Choi and Robert Shrock
hep-th hep-ph