Search for the associated production of the Higgs boson with a top quark pair in multilepton final states with the ATLAS detector Aad, G. Aguilar Saavedra, Juan Antonio Atlas Collaboration Atlas detector Higgs boson Quark pair Astronomy Astrophysics Physics Paticles A search for the associated production of the Higgs boson with a top quark pair is performed in multilepton final states using 20.3 fb−1 of proton–proton collision data recorded by the ATLAS experiment at View the MathML sources=8 TeV at the Large Hadron Collider. Five final states, targeting the decays H→WW⁎H→WW⁎, ττ , and ZZ⁎ZZ⁎, are examined for the presence of the Standard Model (SM) Higgs boson: two same-charge light leptons (e or μ) without a hadronically decaying τ lepton; three light leptons; two same-charge light leptons with a hadronically decaying τ lepton; four light leptons; and one light lepton and two hadronically decaying τ leptons. No significant excess of events is observed above the background expectation. The best fit for the View the MathML sourcett¯H production cross section, assuming a Higgs boson mass of 125 GeV, is View the MathML source2.1−1.2+1.4 times the SM expectation, and the observed (expected) upper limit at the 95% confidence level is 4.7 (2.4) times the SM rate. The p-value for compatibility with the background-only hypothesis is 1.8σ; the expectation in the presence of a Standard Model signal is 0.9σ. 2015-12-11T09:46:09Z 2015-12-11T09:46:09Z 2015 info:eu-repo/semantics/article Atlas Collaboration. Search for the associated production of the Higgs boson with a top quark pair in multilepton final states with the ATLAS detector. Physics Letters B, 749: 519-541 (2015). [http://hdl.handle.net/10481/39170] 0370-2693 1873-2445 http://hdl.handle.net/10481/39170 10.1016/j.physletb.2015.07.079 eng http://creativecommons.org/licenses/by-nc-nd/3.0/ info:eu-repo/semantics/openAccess Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License Elsevier