Electroweak corrections to $pp \to \mu^+\mu^-e^+e^- + X$ at the LHC -- a   Higgs background study
  The first complete calculation of the next-to-leading-order electroweak corrections to four-lepton production at the LHC is presented, where all off-shell effects of intermediate Z bosons and photons are taken into account. Focusing on the mixed final state $\mu^+\mu^-e^+e^-$, we study differential cross sections that are particularly interesting for Higgs-boson analyses. The electroweak corrections are divided into photonic and purely weak corrections. The former exhibit patterns familiar from similar W/Z-boson production processes with very large radiative tails near resonances and kinematical shoulders. The weak corrections are of the generic size of 5% and show interesting variations, in particular a sign change between the regions of resonant Z-pair production and the Higgs signal. 
B.Biedermann, A.Denner, S.Dittmaier, L.Hofer, B.J\"ager
hep-ph