Perturbative QCD effects and the search for a H → WW → lvlv signal at the Tevatron

The Tevatron experiments have recently excluded a Standard Model Higgs boson in the mass range 160GeV < m(H) < 170GeV at the 95% confidence level. This result is based on sophisticated analyses designed to maximize the ratio of accepted signal to background. In this paper we study the production of a Higgs boson of mass m(H) = 160GeV in the gg -> H -> WW -> lvlv channel. We choose a set of cuts like those adopted in the experimental analysis and compare kinematical distributions of the final state leptons computed in NNLO QCD to lower-order calculations and to those obtained with the event generators PYTHIA, HERWIG and MC@ NLO. We also show that the distribution of the output from an Artificial Neural Network obtained with the different tools does not show significant differences. However, the final acceptance computed with PYTHIA is smaller than those obtained at NNLO and with HERWIG and MC@ NLO. We also investigate the impact of the underlying event and hadronization on our results.