Exact Results in Renormalization of Softly Broken SUSY Gauge Theories
It is shown that softly broken theory is equivalent to a rigid theory in external spurion superfield. The singular part of effective action in a broken theory follows from a rigid one by a simple redefinition of the couplings. This gives an explicit relation between the soft and rigid couplings renormalizations. As an illustration the renormalization group functions in the MSSM have been calculated. The method opens a possibility to construct a totally all loop finite N=1 SUSY gauge theory, including the soft SUSY breaking terms. Explicit relations between the soft terms, which lead to a completely finite theory in any loop order, are given.