Combination of Tevatron Searches for the Standard Model Higgs Boson in theW+W−Decay Mode

Abstract

We combine searches by the CDF and D0 Collaborations for a Higgs boson decaying to W+W-. The data correspond to an integrated total luminosity of 4.8 (CDF) and 5.4 (D0) fb(-1) of pp collisions at square root(s) = 1.96 TeV at the Fermilab Tevatron collider. No excess is observed above background expectation, and resulting limits on Higgs boson production exclude a standard model Higgs boson in the mass range 162-166 GeV at the 95% C.L.

Higgs production at the lHC

“…Arguing that these are two theoretical uncertainties that have in principle no statistical ground and should thus not be added in quadrature, we have proposed a more adequate procedure to combine them which led to a total theoretical uncertainty of about ±40% on the gg → H → ℓνℓν signal. This overall uncertainty is much larger than the uncertainty assumed in the CDF and D0 combined analysis that excluded the SM Higgs boson at the 95% CL in the mass range M H = 158-175 GeV [14,15]. To our opinion, this exclusion limit should thus be reconsidered.…”

“…Thus, the PDF uncertainties should be considered as having no statistical ground 14 and they cannot be combined in quadrature with the two other purely theoretical errors, namely the scale and the scheme (EFT) uncertainties. This should be contrasted to what has been done, for instance, by the CDF and D0 collaborations in their combined Higgs analysis at the Tevatron [14,15], where the scale and PDF uncertainties have been added in quadrature. Here, we discuss three possible ways to combine the various uncertainties.…”

“…We then discuss an additional source of theoretical uncertainties that has not been considered neither in the experimental analyses [14,15,18,19] nor in ref. [24]: the one affecting the Higgs decay branching ratios.…”

“…At the Tevatron, the two main search channels for the SM Higgs boson are the top and bottom quark loops mediated gluon-gluon fusion mechanism gg → H [21] with the Higgs decaying into W W pairs which lead to ℓνℓν (with ℓ = e, µ) final states [22] and the Higgs-strahlung processes qq → V H (with V = W, Z) [23] with the subsequent H → bb and V → ℓ + X decays of the Higgs and the associated gauge bosons. Analyses performed by the CDF and D0 experiments, under some assumptions for the production cross sections and their associated uncertainties, have recently excluded the Higgs mass range M H = 158-175 GeV at the 95% confidence level (CL) [14,15]. In this mass range, the Higgs signal is mainly due to the gg → H → W W → ℓνℓν production and decay channels.…”

“…Exclusion limits beyond the well established LEP bounds [13] are now being set on Higgs masses both in the SM [14,15] and in the MSSM [16]. The CERN proton-proton collider successfully started operation but at a reduced center of mass energy of 7 TeV [17].…”