Aaboud, M.Aad, G.Abbott, B.Abdinov, O.Abeloos, B.Abhayasinghe, D. K.Abidi, S. H.Izen, Joseph M.Meirose, BernhardReeves, KendallATLAS collaboration2020-03-042020-03-042019-05-211126-6708http://dx.doi.org/10.1007/JHEP05(2019)124https://hdl.handle.net/10735.1/7341A search for a pair of neutral, scalar bosons with each decaying into two W bosons is presented using 36.1 fb⁻¹ of proton-proton collision data at a centre-of-mass energy of 13 TeV recorded with the ATLAS detector at the Large Hadron Collider. This search uses three production models: non-resonant and resonant Higgs boson pair production and resonant production of a pair of heavy scalar particles. Three final states, classified by the number of leptons, are analysed: two same-sign leptons, three leptons, and four leptons. No significant excess over the expected Standard Model backgrounds is observed. An observed (expected) 95% confidence-level upper limit of 160 (120) times the Standard Model prediction of non-resonant Higgs boson pair production cross-section is set from a combined analysis of the three final states. Upper limits are set on the production cross-section times branching ratio of a heavy scalar X decaying into a Higgs boson pair in the mass range of 260 GeV ≤ mχ ≤ 500 GeV and the observed (expected) limits range from 9.3 (10) pb to 2.8 (2.6) pb. Upper limits are set on the production cross-section times branching ratio of a heavy scalar Χ decaying into a pair of heavy scalars S for mass ranges of 280 GeV ≤ mχ ≤ 340 GeV and 135 GeV ≤ m_{S} ≤ 165 GeV and the observed (expected) limits range from 2.5 (2.5) pb to 0.16 (0.17) pb. © 2019, The Author(s).enCC BY 4.0 (Attribution)©2019 CERN for the benefit of the ATLAS Collaborationhttp://creativecommons.org/licenses/by/4.0/Hadrons--ScatteringBranching ratios (Nuclear physics)Scalar field theoryStandard model (Nuclear physics)Leptons (Nuclear physics)Higgs bosonsLarge Hadron Collider (France and Switzerland)Proton-proton interactionsW bosonsBosonsarticleAaboud, M., G. Aad, B. Abbott, O. Abdinov, et al. 2019. "Search for Higgs boson pair production in the WW(*)WW(*) decay channel using ATLAS data recorded at √s = 13 TeV." Journal of High Energy Physics 2019(5): art. 124, doi: 10.1007/JHEP05(2019)12420195