Production of tt¯bb¯ at the LHC at NLO QCD

We summarise predictions for tt¯bb¯ production at the LHC in next-to-leading order QCD. The precise description of this background process is a prerequisite to observe associated tt¯H production in the H→bb¯ decay channel. The one-loop amplitudes are computed using Feynman diagrams and numerical tensor reduction. This approach provides very high numerical stability and CPU efficiency. We find that the scale choice adopted in ATLAS simulations underestimates the tt¯bb¯ background by a factor two and introduce a new dynamical scale that stabilises the perturbative predictions. In the regime of highly boosted Higgs bosons, which offers better perspectives to observe the tt¯H(H→bb¯) signal, the corrections induce significant distortions in the kinematic distributions.