# Search for the associated production of the Higgs boson with a top quark pair in multilepton final states with the ATLAS detector

Abstract : 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 $\sqrt{s}=8$ TeV at the Large Hadron Collider. Five final states, targeting the decays $H\to WW^*$, $\tau\tau$, and $ZZ^*$, are examined for the presence of the Standard Model (SM) Higgs boson: two same-charge light leptons ($e$ or $\mu$) without a hadronically decaying $\tau$ lepton; three light leptons; two same-charge light leptons with a hadronically decaying $\tau$ lepton; four light leptons; and one light lepton and two hadronically decaying $\tau$ leptons. No significant excess of events is observed above the background expectation. The best fit for the $t\bar t H$ production cross section, assuming a Higgs boson mass of 125 GeV, is $2.1 ^{+1.4}_{-1.2}$ 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 $1.8\sigma$; the expectation in the presence of a Standard Model signal is $0.9\sigma$.
Type de document :
Article dans une revue
Physics Letters B, Elsevier, 2015, 749, pp.519-541. 〈10.1016/j.physletb.2015.07.079〉

http://hal.in2p3.fr/in2p3-01166348
Contributeur : Claudine Bombar <>
Soumis le : lundi 22 juin 2015 - 15:39:26
Dernière modification le : mardi 24 juillet 2018 - 15:46:13

### Citation

G. Aad, Z. Barnovska, N. Berger, M. Delmastro, L. Di Ciaccio, et al.. 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, Elsevier, 2015, 749, pp.519-541. 〈10.1016/j.physletb.2015.07.079〉. 〈in2p3-01166348〉

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