Combined CDF and D0 Upper Limits on Standard Model Higgs Boson Production with up to 8.6 fb-1 of Data

We combine results from CDF and D0 on direct searches for the standard model (SM) Higgs boson (H) in p(bar p) collisions at the Fermilab Tevatron at √s = 1.96 TeV. Compared to the previous Tevatron Higgs boson search combination more data have been added, additional channels have been incorporated, and some previously used channels have been reanalyzed to gain sensitivity. We use the MSTW08 parton distribution functions and the latest theoretical cross sections when comparing our limits to the SM predictions. With up to 8.2 fb-1 of data analyzed at CDF and up to 8.6 fb-1 at D0, the 95% C.L. our upper limits on Higgs boson production are factors of 1.17, 1.71, and 0.48 times the values of the SM cross section for Higgs bosons of mass mH = 115 GeV/c2, 140 GeV/c2, and 165 GeV/c2, respectively. The corresponding median upper limits expected in the absence of Higgs boson production are 1.16, 1.16, and 0.57. There is a small (∼ 1σ) excess of data events with respect to the background estimation in searches for the Higgs boson in the mass range 125 < mH < 155 GeV/c2. We exclude, at the 95% C.L., a new and larger region at high mass between 156 < mH < 177 GeV/c2, with an expected exclusion region of 148 < mH < 180 GeV/c2.