Search for an additional, heavy Higgs boson in the $$H\rightarrow ZZ$$ H → Z Z decay channel at $$\sqrt{s} = 8\;\text{ TeV }$$ s = 8 TeV in $$pp$$ p p collision data with the ATLAS detector

Abstract

A search is presented for a high-mass Higgs boson in the , , , and decay modes using the ATLAS detector at the CERN Large Hadron Collider. The search uses proton–proton collision data at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 20.3 fb. The results of the search are interpreted in the scenario of a heavy Higgs boson with a width that is small compared with the experimental mass resolution. The Higgs boson mass range considered extends up to for all four decay modes and down to as low as 140 , depending on the decay mode. No significant excess of events over the Standard Model prediction is found. A simultaneous fit to the four decay modes yields upper limits on the production cross-section of a heavy Higgs boson times the branching ratio to boson pairs. 95 % confidence level upper limits range from 0.53 pb at GeV to 0.008 pb at GeV for the gluon-fusion production mode and from 0.31 pb at GeV to 0.009 pb at GeV for the vector-boson-fusion production mode. The results are also interpreted in the context of Type-I and Type-II two-Higgs-doublet models.

Interference contributions to gluon initiated heavy Higgs production in the two-Higgs-doublet model

“…For the relevance of other backgrounds we refer to Ref. [58]. A detailed simulation with all backgrounds in order to determine to which cross sections the experiments are actually sensitive at high integrated luminosities is beyond the scope of this paper.…”

“…Scenario S1 is inspired by the ATLAS analysis carried out in Ref. [58], where we want to discuss the relevance of interferences for the per- , and S5 and scenarios S1 and S4 is also the heavy Higgs boson mass. The latter is once above and once below the top threshold 2m t .…”

“…[57,58]. The ATLAS experiment also provided an interpretation in terms of the 2HDM, neglecting possible interferences between the heavy Higgs signal and the background as well as with the contribution of the light Higgs boson.…”

A Heavy Scalar at the LHC from Vector-Boson Fusion

“…Current direct constraints include the 8 TeV LHC bounds such as GGF+VBF ( → ℎ 2 ) × Br(ℎ 2 → gg) ≤ 200 fb [32,33] and GGF+VBF ( → ℎ 2 ) × Br(ℎ 2 → ) ≤ 0.5 fb [34] in the mass region below 200 GeV, as well as VBF ( → ℎ 2 ) × Br(ℎ 2 → ZZ) [16] and VBF ( → ℎ 2 ) × Br(ℎ 2 → WW) [17] in the mass region above 200 GeV. For illustration, we have shown in Figure 2 direct constraint on mixing angle in low mass region.…”

“…Early constraints [8][9][10] on the model parameters were obtained according to measurements on SM Higgs couplings, decay width, and direct detection at the LHC. Updated analyses based on the 8 TeV LHC data [11][12][13][14][15][16][17] can be found in [18][19][20][21][22][23].…”