  The transverse momentum distribution of low-mass Drell-Yan pairs is
calculated in QCD perturbation theory with all-order resummation. We argue that
at LHC energies the results should be reliable for the entire transverse
momentum range. We demonstrate that the transverse momentum distribution of
low-mass Drell-Yan pairs is an advantageous source of constraints on the gluon
distribution and its nuclear dependence.
