  The dilepton decay channels provide clean signatures and are an ideal hunting
ground for high mass resonant, like Z', or non-resonant, like contact
interactions or extra dimensions, searches at the LHC. The production of high
invariant mass opposite sign lepton pairs in proton-proton collisions in the
Standard Model is dominated by the Drell-Yan process. In addition to this
photon or Z exchange mediated mechanism, photons radiated by the incoming
protons can collide and produce lepton pairs. In this paper detailed
calculations of the Drell-Yan process at next-to-next-to-leading order in QCD
and next-to-leading order in the electroweak corrections, augmented with the
photon-induced effects, are presented in the typical acceptance of a
multi-purpose LHC detector at center of mass energy 13 TeV. Estimates of the
expected backgrounds for new physics searches are provided for dilepton
invariant masses up to the LHC kinematic limit.
