Abstract
A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons ({mathrm{H}}) in proton-proton collisions collected by the CMS experiment at the LHC at sqrt{s}=8,text {TeV} . The data correspond to an integrated luminosity of 19.7,text {fb}^{-1}. The search considers {mathrm{H}} {mathrm{H}} resonances with masses between 1 and 3,text {TeV}, having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and {mathrm{t}}overline{{mathrm{t}}} events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 % confidence level for the product of the production cross section and branching fraction sigma ({{mathrm{g}} {mathrm{g}}} rightarrow mathrm {X}), mathcal {B}({mathrm {X}} rightarrow {mathrm{H}} {mathrm{H}} rightarrow {mathrm{b}} overline{{mathrm{b}}} {mathrm{b}} overline{{mathrm{b}}} ) range from 10 to 1.5text {,fb} for the mass of X from 1.15 to 2.0,text {TeV}, significantly extending previous searches. For a warped extra dimension theory with a mass scale Lambda _mathrm {R} = 1 ,text {TeV}, the data exclude radion scalar masses between 1.15 and 1.55,text {TeV}.
Highlights
IntroductionThe warped extra dimension (WED) theory predicts a cross section that can be detected at the LHC [17], but is challenged by the constraints derived from the electroweak precision measurements [29]
The production of pairs of Higgs bosons (H) in the standard model (SM√) gluon fusion at s has a predicted cross = 8 TeV [1,2] for the section in gluon– Higgs boson mass mH ≈ 125 GeV [3] of only 10.0±1.4 fb
Many BSM theories suggest the existence of narrow heavy particles X that can decay to a pair of Higgs bosons [4,5,6,7,8,9,10,11,12]
Summary
The WED theory predicts a cross section that can be detected at the LHC [17], but is challenged by the constraints derived from the electroweak precision measurements [29]. This specific model is excluded up to mX = 1.1 TeV by the previous X → HH searches [14,17]. The H candidates are selected by employing jet substructure techniques to identify jets containing constituents with kinematics consistent with the decay of a highly boosted Higgs boson. The signal is identified in the dijet mass (mjj) spectrum as a peak above a falling background which originates mainly from multijet events and tt production
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