  We derive a factorization formula for the production of pairs of heavy
coloured particles in hadronic collisions near the production threshold that
establishes factorization of soft and Coulomb effects. This forms the basis for
a combined resummation of Coulomb and soft corrections, including the
non-trivial interference of the two effects. We develop a resummation formalism
valid at NNLL accuracy using the momentum-space approach to soft gluon
resummation. We present numerical results for the NLL resummed
squark-antisquark production cross section at the LHC and Tevatron, including
also the contribution of squark-antisquark bound states below threshold. The
total correction on top of the next-to-leading order approximation is found to
be sizeable, and amounts to (4-20)% in the squark mass region 200 GeV-3 TeV at
the 14 TeV LHC. The scale dependence of the total cross section is also
reduced.
