W+Z and W+γ∗ backgrounds to strong W+W+ scattering at the LHC

Because of inevitable blind spots at high rapidity and low transverse momentum, the process qq → l+l−l+ν provides a surprisingly large background to the W+W+ → l+νl+ν signal associated with strong WW scattering. Previous calculations of the total background are approximately doubled, and the estimate of the “no-lose” luminosity at the LHC to observe manifestations of the electroweak symmetry breaking mechanism is increased to between ∼100 and ∼140 fb−1.