H→WW as the discovery mode for a light Higgs boson

Abstract

The production cross section for a m H ≈ 115 GeV, SM Higgs boson in weak boson fusion at the LHC is sizable. However, the branching fraction for H → W + W − is expected to be relatively small. The signal, with its two forward jets, is sufficiently different from the main backgrounds that a signal to background ratio of better than 1:1 can nevertheless be obtained, with large enough rate to allow for a 5σ signal with 35 fb −1 of data. The H → W W signal in weak boson fusion may thus prove to be the discovery mode for the Higgs boson at the LHC.After the end of LEP II running, the search for the Higgs boson and, hence, for the origin of electroweak symmetry breaking and fermion mass generation, remains one of the premier tasks of present and future high energy physics experiments. With the exclusion of a SM Higgs boson of mass m H < 113.5 GeV and some evidence for m H ≈ 115 GeV [1], the mass range now preferred by supersymmetry [2,3], 113 GeV < ∼ m h < ∼ 130 GeV, will likely remain the focus of investigations until the beginning of data taking at the CERN LHC.Previously we have shown that a somewhat heavier Higgs boson, in the range 130 GeV < ∼ m H < ∼ 190 GeV, will give a highly significant H → W + W − → e ± µ ∓ p / T signal in weak boson fusion (WBF) at the LHC [4,5]. For a smaller Higgs boson mass, the branching ratio of the H → W + W − mode quickly decreases, making the observation of this mode more difficult. Only a marginal signal was expected for m H ≈ 115 GeV. However, this earlier analysis was optimized for a Higgs boson mass near W -pair threshold and can clearly be improved for the significantly smaller masses favored at the end of LEP II running. This situation motivates a complete reanalysis of possible H → W + W − signals in WBF at the LHC, and of possible backgrounds, with the goal of optimizing the significance of a signal for m H ≈ 115 GeV. At the same time a better signal to background (S/B) ratio, higher signal acceptance and higher accuracy in the determination of Bσ(qq → qqH, H → W W ) would significantly improve the extraction of Higgs boson properties such as its total width or the HW W coupling constant [6].In this letter we summarize the results of this reanalysis, and show that even for a SM Higgs of 1

Prospects for new physics observations in diffractive processes at the LHC and Tevatron

“…The allowed mass window is claimed to be [25][26][27][28][29][30][31][32][33][34][35] GeV. Within such a scenario there should exist a spectrum ofgg bound states (gluinoballs or gluinonia), which may reveal themselves in gluon-gluon collisions.…”

Higgs boson decay into hadronic jets

“…The weak boson fusion modes [40] can be an effective means to search for the decays h → W + W − and h → τ + τ − . As in the case of tth, because the couplings of h to W and Z are approximately standard in the decoupling limit, the production cross sections are basically the same as in the SM, and the primary influence of the light bottom squark is to depress the branching ratios into the distinctive decay modes in favor of decay into jets.…”

Measuring Higgs $ \mathcal{C}\mathcal{P} $ and couplings with hadronic event shapes

“…To establish that a single Higgs field is responsible for the generation of fermion and electroweak-gauge-boson masses, eventually, the couplings of the Higgs boson to all SM particles have to be measured accurately. The major production processes of a light Higgs boson at the LHC are the gluon fusion (GF) [17] and the weak boson fusion (WBF) [18,19] channels. The GF channel is induced by heavy fermion loops connecting the initial state gluons with the Higgs boson, while the WBF channel relies on the large Higgs coupling to electroweak gauge bosons to produce the Higgs in association with two tagging jets.…”