Preprints

Searches for the exclusive decays of the Higgs and $Z$ bosons into a $J/ψ , ψ(2S)$ , or $ϒ(nS) ( n=1,2,3 )$ meson and a photon are performed with a pp collision data sample corresponding to an integrated luminosity of 36.1 fb$^{−1}$ collected at $\sqrt{s}=$ 13TeV with the ATLAS detector at the CERN Large Hadron Collider. No significant excess of events is observed above the expected backgrounds, and 95% confidence-level upper limits on the branching fractions of the Higgs boson decays to $J/ψγ , ψ(2S)γ$ , and $ϒ(nS)γ$ of $3.5×10^{−4} , 2.0 × 10^{−3}$ , and $(4.9,5.9,5.7) × 10^{−4}$ , respectively, are obtained assuming Standard Model production. [...]

A search for the $b\bar{b}$ decay of the Standard Model Higgs boson produced through vector-boson fusion is presented. Three mutually exclusive channels are considered: two all-hadronic channels and a photon-associated channel. [...]

The elliptic flow of prompt and non-prompt $J/\psi $ was measured in the dimuon decay channel in Pb+Pb collisions at $\sqrt{s_{_\text {NN}}}=5.02$   $\text {TeV}$ with an integrated luminosity of $0.42~\mathrm {nb}^{-1}$ with the ATLAS detector at the LHC. The prompt and non-prompt signals are separated using a two-dimensional simultaneous fit of the invariant mass and pseudo-proper decay time of the dimuon system from the $J/\psi $ decay. [...]

Charged Higgs bosons produced either in top-quark decays or in association with a top-quark, subsequently decaying via H$^{±}$ → τ$^{±}$ν$_{τ}$, are searched for in 36.1 fb$^{−1}$ of proton-proton collision data at $ \sqrt{s}=13 $ TeV recorded with the ATLAS detector. Depending on whether the top-quark produced together with H$^{±}$ decays hadronically or leptonically, the search targets τ+jets and τ+lepton final states, in both cases with a hadronically decaying τ-lepton. [...]

This Letter presents a search for the production of a long-lived neutral particle decaying within the ATLAS hadronic calorimeter, in association with a Standard Model $Z$ boson produced via an intermediate scalar boson, where $Z \rightarrow l^+ l^-$ ($l=e,\mu$). The data used were collected by the ATLAS detector during 2015 and 2016 $pp$ collisions with a center-of-mass energy of $\sqrt{s} = 13$ TeV at the Large Hadron Collider and corresponds to an integrated luminosity of 36.1 fb$^{-1}$. [...]

The Level-1 Muon Barrel Trigger of the ATLAS Experiment at LHC makes use of Resistive Plate Chamber (RPC) detectors. The on-detector trigger electronics modules are able to identify muons with predefined transverse momentum values (pT) by executing a coincidence logic on signals coming from the various detector layers. [...]

A measurement of off-shell Higgs boson production in the $ZZ\to4\ell$ and $ZZ\to2\ell2\nu$ decay channels, where $ℓ$ stands for either an electron or a muon, is performed using data from proton–proton collisions at a centre-of-mass energy of $\sqrt{s}=$13 TeV. The data were collected by the ATLAS experiment in 2015 and 2016 at the Large Hadron Collider, and they correspond to an integrated luminosity of 36.1fb$^{−1}$ [...]

Searches for new heavy resonances decaying into different pairings of $W$, $Z$, or Higgs bosons, as well as directly into leptons, are presented using a data sample corresponding to 36.1fb$^{-1}$ of $pp$ collisions at $\sqrt{s}$ = 13 TeV collected during 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. Analyses selecting bosonic decay modes in the $qqqq$, $\nu\nu qq$, $\ell\nu qq$, $\ell\ell qq$, $\ell\nu\ell\nu$, $\ell\ell\nu\nu$, $\ell\nu\ell\ell$, $\ell\ell\ell\ell$, $qqbb$, $\nu\nu bb$, $\ell\nu bb$, and $\ell\ell bb$ final states are combined, searching for a narrow-width resonance. [...]

This document summarises the expected ATLAS sensitivity to four top-quark signatures in models involving two Higgs doublets and an additional pseudo-scalar mediator that couples to dark matter particles. The sensitivity is estimated using 3000 fb$^{−1}$ of proton-proton collisions in the context of the High Luminosity LHC update. [...]

A search is presented for decays of Z and Higgs bosons to a J$/\psi$ meson and a photon, with the subsequent decay of the J$/\psi$ to $\mu^+\mu^-$. The analysis uses data from proton-proton collisions with an integrated luminosity of 35.9 fb$^{-1}$ at $\sqrt{s}=$ 13 TeV collected with the CMS detector at the LHC. [...]