Abstract
New results for the complete one-loop contributions to the masses and
mixing effects in the Higgs sector are obtained for the MSSM with
complex parameters using the Feynman-diagrammatic approach.
The full dependence on all relevant complex phases
is taken into account, and all the imaginary parts appearing in the
calculation are treated in a consistent way.
The renormalization is discussed in detail, and a hybrid
on-shell/
scheme is adopted.
We also derive the wave function normalization factors needed in
processes with external Higgs bosons and discuss effective couplings
incorporating leading higher-order effects.
The complete one-loop corrections, supplemented by the available
two-loop corrections in the Feynman-diagrammatic approach for the
MSSM with real parameters and a resummation of the leading (s)bottom
corrections for complex parameters, are implemented into the public Fortran
code FeynHiggs 2.5.
In our numerical analysis the full results
for the Higgs-boson masses and couplings are compared with various
approximations, and 
-violating effects in the mixing of the heavy Higgs
bosons are analyzed in detail. We find sizable deviations in comparison
with the approximations often made in the literature.