Production of heavy quarks from W-gluon fusion

We show that heavy-quark production via W-gluon fusion in high-energy pp and p»p collisions is an important source of the heavier member of an SU(2)L doublet of quarks if the mass splitting within the doublet is large. W-gluon fusion exceeds the strong production of heavy quarks for mass splittings greater than 300350 GeV at s =10 TeV and 400450 GeV at s =40 TeV. An alternative way to regard W-gluon fusion is as the production of the heavier quark by fusing its light partner with a W boson. We use a distribution function for the light partner to show that this process gives results which agree qualitatively with W-gluon fusion. We also discuss the Drell-Yan production of an SU(2)L doublet of heavy quarks via a virtual W boson and corrections to this process from initial gluons. We find that at the Fermilab Tevatron energy s =2 TeV, W-gluon fusion exceeds the Drell-Yan production of top quarks for masses above 100 GeV.