  A compact approximation formula for the mass of the lightest neutral CP-even
Higgs boson, m_h, in the Minimal Supersymmetric Standard Model (MSSM) is
derived from the diagrammatic two-loop result for m_h up to O(alpha alpha_s).
By analytically expanding the diagrammatic result the leading logarithmic and
non-logarithmic as well as the dominant subleading contributions are obtained.
The approximation formula is valid for general mixing in the scalar top sector
and arbitrary choices of the parameters in the Higgs sector of the model. Its
quality is analyzed by comparing it with the full diagrammatic result. We find
agreement with the full result better than 2 GeV for most parts of the MSSM
parameter space.

High Energy Physics - Phenomenology