YUKAWA CORRECTION TO TOP-QUARK PRODUCTION AT THE FERMILAB TEVATRON

We calculate the correction to qqBAR --> ttBAR of order g2m(t)2/M(W)2. This correction, proportional to the square of the Higgs-boson Yukawa coupling to the top quark, arises from loops of Higgs bosons and the scalar component of virtual vector bosons. The Yukawa correction to th e total ttBAR production cross section at the Fermilab Tevatron in the standard Higgs model is found to be much less than the theoretical un certainty in the cross section. However, in a two-Higgs-doublet model, Yukawa couplings are generally enhanced. The Yukawa correction can in crease the total ttBAR production cross section in this model by as mu ch as 20-35 %, which is potentially observable at the Tevatron.