We recently proposed that, due to the top-quark-mass enhanced Yukawa
coupling, the s-channel production of a charged scalar or pseudo-scalar from
heavy quark fusion can be an important new mechanism for discovering
non-standard spin-0 particles. In this work, we present the complete O(alpha_s)
QCD corrections to this s-channel production process at hadron colliders,
including the results of QCD resummation over multiple soft-gluon emission. The
systematic QCD-improved production and decay rates at the FermiLab Tevatron and
the CERN LHC are given for the charged top-pions in the topcolor models and for
the charged Higgs bosons in the generic two Higgs doublet model. The direct
extension to the production of the neutral (pseudo-)scalars via bb\bar fusion
is studied in the minimal supersymmetric standard model (MSSM) with large
tan(beta), and in the topcolor model with large bottom Yukawa coupling.Comment: Version to be published in Phys.Rev.D. Discussion on Rb added plus
minor improvements. Conclusions not changed. Latex2e, 40 pages, 16 figure