Two-loop radiative corrections to the mass of the lightest Higgs boson in supersymmetric standard models

We compute the two-loop corrections to the mass of the lightest Higgs boson ( m h ), in the minimal and non-minimal (including a gauge singlet) supersymmetric standard model, when the scale of supersymmetry breaking ( M SUSY ) is larger than the electroweak scale. We use the effective potential in the leading logarithm approximation and renormalization group techniques. We find that, even in cases where the one-loop correction is larger than the tree-level mass, the two-loop correction stays within a few percent. We present, for minimal and non-minimal models, two-loop upper bounds, which depend on the top-quark mass ( m t ), and M SUSY . These theoretical bounds, along with future experimental bounds on m t and m h , could be used to push M SUSY towards higher scales.