Four-lepton production at hadron colliders: aMC@NLO predictions with   theoretical uncertainties
  We use aMC@NLO to study the production of four charged leptons at the LHC, performing parton showers with both HERWIG and Pythia6. Our underlying matrix element calculation features the full next-to-leading order $O(\alpha_S)$ result and the $O(\alpha_S^2)$ contribution of the $gg$ channel, and it includes all off-shell, spin-correlation, virtual-photon-exchange, and interference effects. We present several key distributions together with the corresponding theoretical uncertainties. These are obtained through a process-independent technique that allows aMC@NLO to compute scale and PDF uncertainties in a fully automated way and at no extra CPU-time cost 
Rikkert Frederix, Stefano Frixione, Valentin Hirschi, Fabio Maltoni,   Roberto Pittau, Paolo Torrielli
hep-ph