Search for pair production of Higgs bosons in the $$ b\overline{b}b\overline{b} $$ final state using proton-proton collisions at $$ \sqrt{s}=13 $$ TeV with the ATLAS detector

Abstract

Search for pair production of Higgs bosons in the bbbb final state using proton-proton collisions at √ s = 13 TeV with the ATLAS detectorThe ATLAS Collaboration A search for Higgs boson pair production in the bbbb final state is carried out with up to 36.1 fb −1 of LHC proton-proton collision data collected at √ s = 13 TeV with the ATLAS detector in 2015 and 2016. Three benchmark signals are studied: a spin-2 graviton decaying into a Higgs boson pair, a scalar resonance decaying into a Higgs boson pair, and Standard Model non-resonant Higgs boson pair production. Two analyses are carried out, each implementing a particular technique for the event reconstruction that targets Higgs bosons reconstructed as pairs of jets or single boosted jets. The resonance mass range covered is 260-3000 GeV. The analyses are statistically combined and upper limits on the production cross section of Higgs boson pairs times branching ratio to bbbb are set in each model. No significant excess is observed; the largest deviation of data over prediction is found at a mass of 280 GeV, corresponding to 2.3 standard deviations globally. The observed 95% confidence level upper limit on the non-resonant production is 13 times the Standard Model prediction.The discovery of the Standard Model (SM) Higgs boson (H) [1, 2] at the Large Hadron Collider (LHC) motivates searches for new physics using the Higgs boson as a probe. In particular, many models predict cross sections for Higgs boson pair production that are significantly greater than the SM prediction. Resonant Higgs boson pair production is predicted by models such as the bulk Randall-Sundrum model [3,4], which features spin-2 Kaluza-Klein gravitons, G KK , that subsequently decay to pairs of Higgs bosons. Extensions of the Higgs sector, such as two-Higgs-doublet models [5,6], propose the existence of a heavy spin-0 scalar that can decay into H pairs. Enhanced non-resonant Higgs boson pair production is predicted by other models, for example those featuring light coloured scalars [7] or direct ttHH vertices [8,9].Previous searches for Higgs boson pair production have all yielded null results. In the bbbb channel, ATLAS searched for both non-resonant and resonant production in the mass range 400-3000 GeV using 3.2 fb −1 of 13 TeV data [10] collected during 2015. CMS searched for the production of resonances with masses 750-3000 GeV using 13 TeV data [11] and with masses 270-1100 GeV with 8 TeV data [12]. Using 8 TeV data, ATLAS has examined the bbbb [13], bbγγ [14], bbτ + τ − and W + W − γγ channels, all of which were combined in Ref. [15]. CMS has performed searches using 13 TeV data for the bbτ + τ − [16] and bb ν ν [17] final states, and used 8 TeV data to search for bbγγ [18] in addition to a search in multilepton and multilepton+photons final states [19].The analyses presented in this paper exploit the decay mode with the largest branching ratio, H → bb, to search for Higgs boson pair production in both resonant and non-resonant production. Two analyses, which are complementary in the...

Probing pseudo-Goldstone dark matter at the LHC

“…• The ATLAS searches for h 2 → h 1 h 1 in 4b [39], 2γ 2b [40] and 2W 2γ final states, and the CMS searches in 2γ 2b [41] and 4b [42] final states. The ATLAS searches and the CMS 4b search probe the heavy Higgs masses above 260 GeV and the CMS 2γ 2b search probes those above 250 GeV.…”

Portraying double Higgs at the Large Hadron Collider

“…In order to access κ 3 (κ 4 ), one has to measure the process of double (triple) Higgs boson production at the LHC, possibly with high luminosity (HL), or at future colliders. Double Higgs (hh) production has been studied in many channels, including bbbb [13][14][15][16][17][18], bbγγ [6,10,[19][20][21][22][23][24][25][26][27][28][29][30][31], bbτ τ [6,21,[32][33][34][35][36], bbW + W − /ZZ [8,9,[37][38][39][40][41], W + W − W + W − [42], etc. Among the different possible final states, here we focus on hh production at the HL-LHC in the final state with two b-tagged jets, two leptons and missing transverse momentum.…”

Di-Higgs production in the 4b channel and gravitational wave complementarity

“…In contrast, in this work, we analyze another potentially major channel that can discover h 2 at the LHC complementing the collider studies of our previous two papers mentioned above. Our estimate of the LHC sensitivity to this channel benefits from a reliable background estimation from the recent ATLAS search for double Higgs production and decay to 4b-tagged jets [16]. There has been a similar 4b analysis in the literature in connection with EWPT [17] using several benchmarks, which, however, does not include GW analysis.…”

“…L = 3 ab −1 , sin θ = 0.2 Background full GF xSM full GF xSM resonant GF SM m hh distribution for the GF components: SM (yellow), xSM resonant (red), and xSM full that accounts for the resonant and non-resonant contributions (blue). The total background component obtained from ATLAS via a data driven approach is also shown (black)[16]. The signal sample is simulated with a Heavy Higgs mass m h 2 = 800 GeV, v s = 24.8 GeV, b 3 /v EW = −10, b 4 = 4.2, and mixing sin θ = 0.2.…”