Next-to-leading order corrections to single top quark production and decay at the Fermilab Tevatron. II. t-channel process

We present a study of $s$-channel single top quark production at the upgraded Tevatron $p\overline{p}$ collider, including the next-to-leading order (NLO) QCD corrections to the production and decay of the top quark. The modified narrow width approximation was adopted to preserve the spin of the top quark in its production and decay. We discuss the effect of the different $O({\ensuremath{\alpha}}_{s})$ contributions on the inclusive cross section as well as various kinematical distributions after imposing the relevant cuts to select $s$-channel single top signal events. In particular, the $O({\ensuremath{\alpha}}_{s})$ decay contribution, while small in size, has a significant impact on several distributions. With the help of the best-jet algorithm to reconstruct the top quark, we demonstrate that it is possible to study kinematical and spin correlations in $s$-channel single top events. We furthermore compare top quark spin measurements in two different bases and show how NLO corrections have to be taken into consideration in searches for the Higgs boson through ${W}^{\ifmmode\pm\else\textpm\fi{}}H$ associated production at the Tevatron.