Jeroen Schouwenberg

Evidence for the associated production of the Higgs boson and a top quark pair with the ATLAS detector

A search for the associated production of the Higgs boson with a top quark pair (tt̄H) is reported. The search is performed in multilepton final states using a dataset corresponding to an integrated luminosity of 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at a center-of-mass energy √ s = 13 TeV at the Large Hadron Collider. Higgs boson decays toWW∗, ττ, and Z Z∗ are targeted. Seven final states, categorized by the number and flavor of charged-lepton candidates, are examined for the presence of the Standard Model Higgs boson with a mass of 125 GeV and a pair of top quarks. An excess of events over the expected background from Standard Model processes is found with an observed significance of 4.1 standard deviations, compared to an expectation of 2.8 standard deviations. The best fit for the tt̄H production cross section is σ(tt̄H) = 790+230 −210 fb, in agreement with the Standard Model prediction of 507+35 −50 fb. The combination of this result with other tt̄H searches from the ATLAS experiment using the Higgs boson decay modes to bb̄, γγ and Z Z∗ → 4`, has an observed significance of 4.2 standard deviations, compared to an expectation of 3.8 standard deviations. This provides evidence for the tt̄H production mode.

Search for long-lived, massive particles in events with displaced vertices and missing transverse momentum in s =13 TeV pp collisions with the ATLAS detector

A search for long-lived, massive particles predicted by many theories beyond the Standard Model is presented. The search targets final states with large missing transverse momentum and at least one high-mass displaced vertex with five or more tracks, and uses 32.8 fb−1 of √ s = 13 TeV pp collision data collected by the ATLAS detector at the LHC. The observed yield is consistent with the expected background. The results are used to extract 95% CL exclusion limits on the production of long-lived gluinos with masses up to 2.37 TeV and lifetimes of O(10−2)–O(10) ns in a simplified model inspired by Split Supersymmetry.

Search for heavy resonances decaying into a W or Z boson and a Higgs boson in final states with leptons and b-jets in 36 fb(-1) of √s = 13 TeV pp collisions with the ATLAS detector

A bstractA search is conducted for new resonances decaying into a W or Z boson and a 125 GeV Higgs boson in the νν¯bb¯

Searches for the Zγ decay mode of the Higgs boson and for new high-mass resonances in pp collisions at √s=13 TeV with the ATLAS detector

\nu \overline{\nu}b\overline{b}

Measurement of differential cross-sections of a single top quark produced in association with a W boson at √s = 13 TeV with ATLAS

, ℓ±νbb¯

Measurement of the kt splitting scales in Z → ℓℓ events in pp collisions at s=8 TeV with the ATLAS detector

{\ell}^{\pm}\nu b\overline{b}