  The production of lepton pairs at low invariant mass and finite transverse
momentum resolves QCD dynamics at the boundary between the perturbative and
non-perturbative domains. We investigate the impact of NNLO QCD corrections on
these observables at energies corresponding to the BNL RHIC collider and to
fixed-target experiments. Satisfactory perturbative convergence is observed in
both cases. Only the collider data are found to be well-described by
perturbative QCD, thus indicating the importance of non-perturbative effects in
lepton-pair transverse momentum distributions at fixed target energies.
