Yukawa Corrections to Single Top Quark Production at the Fermilab   Tevatron in the Two-Higgs-Doublet Models
  We calculate Yukawa corrections of order $\alpha_{ew} M_t^2/M_W^2$ to single top quark production via $q \bar q'\rightarrow t \bar b$ at the Fermilab Tevatron in the two-Higgs-doublet models. In our calculation we also keep the terms proportional to $ M_b^2 \tan^2 \beta$ since their effects may become rather important for large $\tan\beta$. The corrections can amount to more than a 15\% reduction in the production cross section relative to the tree level result in the general two-Higgs-doublet model, and a 10\% enhancement in the minimal supersymmetric model, which might be observable at a high-luminosity Tevatron. 
Chong Sheng Li, Robert J. Oakes and Jin Min Yang