Speaker
Description
The first ATLAS search for non-resonant Higgs boson pair production in association with a top-quark pair ($ttHH$) is presented. The search targets three distinct final states expected from the $ttHH$ decay: (i) one lepton (electron or muon) with at least four b-quarks, (ii) at least two b-quarks accompanied by a same-sign dilepton pair or multiple leptons, and (iii) at least three b-quarks with two photons. The proton-proton collision dataset used corresponds to an integrated luminosity of 196 $\textrm{fb}^{-1}$, consisting of 140 $\textrm{fb}^{-1}$ at a centre-of-mass energy of $\sqrt{s}$ = 13 TeV and 56 $\textrm{fb}^{-1}$ at $\sqrt{s}$ = 13.6 TeV. The $ttHH$ production cross section relative to its Standard Model prediction is found to be $\mu_{ttHH}=−3^{+11}_{-12}$ with its predicted value of $\mu_{ttHH}=1_{-10}^{+10}$. It corresponds to a 95% confidence-level upper limit on the ttHH production cross section of 19.7 times the Standard Model prediction, with an expected limit of 21.2.
| Track | Higgs Physics |
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