Radiative corrections to the Higgs boson mass for a hierarchical stop spectrum

An effective theory approach is used to compute analytically the radiative corrections to the mass of the light Higgs boson of the Minimal Supersymmet ric Standard Model when there is a hierarchy in the masses of the stops (M- (t) over bar1 much greater than M-(t) over bar2 much greater than M-top, wi th moderate stop mixing). The calculation includes up to two-loop leading a nd next-to-leading logarithmic corrections dependent on the QCD and top-Yuk awa couplings, and is further completed by two-loop non-logarithmic correct ions extracted from the effective potential. The results presented disagree already at two-loop-leading-log level with widely used findings of previou s literature. Our formulas can be used as the starting point for a full num erical resummation of logarithmic corrections to all loops, which would be mandatory if the hierarchy between the stop masses is large. (C) 2001 Elsev ier Science B.V. All rights reserved.