We study the factorization and resummation of the ttˉW± 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 logarithms 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.Comment: 23 pages, 7 figures and 2 tables; final version in PR