I present results for the two-loop self-energy functions for scalars in a
general renormalizable field theory, using mass-independent renormalization
schemes based on dimensional regularization and dimensional reduction. The
results are given in terms of a minimal set of loop-integral basis functions,
which are readily evaluated numerically by computers. This paper contains the
contributions corresponding to the Feynman diagrams with zero or one vector
propagator lines. These are the ones needed to obtain the pole masses of the
neutral and charged Higgs scalar bosons in supersymmetry, neglecting only the
purely electroweak parts at two-loop order. A subsequent paper will present the
results for the remaining diagrams, which involve two or more vector lines.Comment: 26 pages, 4 figures, revtex4, axodraw.sty. Version 2: sentence after
eq. (A.13) corrected, references added. Version 3: typos in eqs. (5.17),
(5.20), (5.21), (5.32) are corrected. Also, the MSbar versions of eqs. (5.32)
and (5.33) are now include