  In R-parity conserving supersymmetric (SUSY) models, sleptons are produced in
pairs at hadron colliders through neutral and charged electroweak currents. We
demonstrate that the polarization of the initial hadron beams allows for a
direct extraction of the slepton mixing angle and thus for a determination of
the underlying SUSY-breaking mechanism. We also perform a first precision
calculation of the transverse-momentum (q_T) spectrum of the slepton pairs by
resumming soft multiple-gluon emission at next-to-leading logarithmic order.
The results show a relevant contribution of resummation both in the small and
intermediate q_T-regions, which strongly influences the extraction of the
missing transverse-momentum signal and the subsequent slepton
mass-determination, and little dependence on unphysical scales and
non-perturbative contributions.
