Effects of QCD Resummation on $W^+h$ and $tbar b$ Production at the Tevatron

The resummation of multiple soft gluon emission affects the production rate and kinematic distributions of $W^+h$ (where h is a Higgs boson) and $t bar b$ pairs at the Tevatron with $sqrt{s}=2$ TeV. Using the Collins-Soper-Sterman resummation formalism, the production rate is enhanced over the next-to-leading-order (NLO) prediction by 2-3% for the $W^+h$ process, for Higgs boson masses between 80-120 GeV, and over 3% for the $tbar b$ process for $m_t=175$ GeV. After resummation, the $tbar b$ rate changes by 12-13% when $m_t$ is varied by $pm 5$ GeV. Various kinematic distributions are presented for the individual final state particles and for the pair. The explicit radiation of hard gluons in NLO QCD is included also for the $tbar b$ final state.