Renormalization group improved predictions for t(t)over-barW± production at hadron colliders

We study the factorization and resummation of the t (t) over barW(+/-) production at hadron colliders. The cross section in the threshold limit can be factorized into a convolution of hard and soft functions and parton distribution functions with the soft-collinear effective theory. We calculate the next-to-leading order soft function for the associated production of the heavy quark pair and colorless particle, and we perform the resummation calculation with the next-to-next-to-leading logarithm accuracy. Our results show that the resummation effects reduce the dependence of the cross section on the scales significantly and increase the total cross section by 7%-13% compared with NLO QCD results.