The Higgs Has a Mass of 125 GeV

We combine results from the CDF and D0 Collaborations on direct searches for the standard model
(SM) Higgs boson (H) in p¯p collisions at the Fermilab Tevatron at √s = 1.96 TeV. Compared to the
previous Tevatron Higgs boson search combination, more data have been included in those channels
that hadn’t previously used the full dataset, additional channels have been incorporated, and some
previously used channels have been reanalyzed to gain sensitivity. Searches are carried out for
hypothesized Higgs boson masses between 100 and 200 GeV/c2. With up to 10 fb−1 of luminosity
analyzed, the 95% C.L. median expected upper limits on Higgs boson production are factors of 0.89,
1.08, and 0.48 times the values of the SM cross section for Higgs bosons of mass mH =115 GeV/c2,
125 GeV/c2, and 165 GeV/c2, respectively. In the absence of signal, we expect to exclude the
regions 100 < mH < 120 GeV/c2 and 139 < mH < 184 GeV/c2. We exclude, at the 95% C.L., two
regions: 100 < mH < 103 GeV/c2, and 147 < mH < 180 GeV/c2. There is a significant excess of
data events with respect to the background estimation in the mass range 115 < mH < 140 GeV/c2,
which causes our observed limits to not be as stringent as expected. At mH = 120 GeV/c2, the
p-value for a background fluctuation to produce this excess is ∼1.5×10−3, corresponding to a local
significance of 3.0 standard deviations. The global significance (incorporating the look-elsewhere
effect) for such an excess anywhere in the full mass range investigated is approximately 2.5 standard
deviations. We also combine separately searches for H → b¯b and H → W+W−. We find that the
excess is concentrated in the H → b¯b channel, appearing in the searches over a broad range of mH.
The maximum local significance of 3.2 standard deviations corresponds to a global significance of
approximately 2.9 standard deviations. Our results in the H → W+W− channels are also consistent
with the possible presence of a low-mass Higgs boson.

arXiv