216 research outputs found

    Search for pair production of squarks or gluinos decaying via sleptons or weak bosons in final states with two same-sign or three leptons with the ATLAS detector

    Get PDF
    A search for pair production of squarks or gluinos decaying via sleptons or weak bosons is reported. The search targets a final state with exactly two leptons with same-sign electric charge or at least three leptons without any charge requirement. The analysed data set corresponds to an integrated luminosity of 139fb−1 of proton-proton collisions collected at a centre-of-mass energy of 13TeV with the ATLAS detector at the LHC. Multiple signal regions are defined, targeting several SUSY simplified models yielding the desired f inal states. A single control region is used to constrain the normalisation of the WZ +jets background. No significant excess of events over the Standard Model expectation is observed. The results are interpreted in the context of several supersymmetric models featuring R-parity conservation or R-parity violation, yielding exclusion limits surpassing those from previous searches. In models considering gluino (squark) pair production, gluino (squark) masses up to 2.2 (1.7) TeV are excluded at 95% confidence leve

    Search for light long-lived neutral particles from Higgs boson decays via vector-boson-fusion production from pp collisions at s=13\sqrt{s}=13 TeV with the ATLAS detector

    Get PDF

    Search for heavy neutral Higgs bosons decaying into a top quark pair in 140 fb−1 of proton-proton collision data at s \sqrt{s} = 13 TeV with the ATLAS detector

    Get PDF

    Search for the jet-induced diffusion wake in the quark-gluon plasma via measurements of jet-track correlations in photon-jet events in Pb+Pb collisions at sNN=5.02TeV with the ATLAS detector

    Get PDF
    This paper presents a measurement of jet-track correlations in photon-jet events, using 1.72 nb^(-1) of Pb+Pb data at root(sNN) = 5.02 TeV recorded with the ATLAS detector at the LHC. Events with energetic photon-jet pairs are selected, where the photon and jet are approximately back-to-back in azimuth. The angular correlation between jets and charged-particle tracks with transverse momentum (pT) in the range 0.5-2.0 GeV in the hemisphere opposite to the jet, | phi(jet,track)| > pi/2, is measured as a function of their relative pseudorapidity difference, | eta(jet,track)|. In central Pb+Pb collisions, these correlations are predicted to be sensitive to the diffusion wake in the quark-gluon plasma resulting from the lost energy of high-pT partons traversing the plasma, with a characteristic modification as a function of | eta(jet,track)|. The correlations are examined with different selections on the jet-to-photon pT ratio to select events with different degrees of energy loss. No diffusion wake signal is observed within the current sensitivity and upper limits at 95% confidence level on the diffusion wake amplitude are reported

    Statistical Combination of ATLAS Run 2 Searches for Charginos and Neutralinos at the LHC

    Get PDF
    Statistical combinations of searches for charginos and neutralinos using various decay channels are performed using 139 fb^{-1} of pp collision data at sqrt[s]=13 TeV with the ATLAS detector at the Large Hadron Collider. Searches targeting pure-wino chargino pair production, pure-wino chargino-neutralino production, or Higgsino production decaying via standard model W, Z, or h bosons are combined to extend the mass reach to the produced supersymmetric particles by 30-100 GeV. The depth of the sensitivity of the original searches is also improved by the combinations, lowering the 95% C.L. cross-section upper limits by 15%-40%

    Measurement of the VH,H → ττ process with the ATLAS detector at 13 TeV

    Get PDF
    A measurement of the Standard Model Higgs boson produced in association with a W or Z boson and decaying into a pair of tau-leptons is presented. This search is based on proton-proton collision data collected at root s = 13 TeV by the ATLAS experiment at the LHC corresponding to an integrated luminosity of 140 fb-1. For the Higgs boson candidate, only final states with at least one tau-lepton decaying hadronically (tau -> hadrons + nu(tau)) are considered. For the vector bosons, only leptonic decay channels are considered: Z -> ll and W -> l nu(l), with l = e, mu. An excess of events over the expected background is found with an observed (expected) significance of 4.2 (3.6) standard deviations, providing evidence of the Higgs boson produced in association with a vector boson and decaying into a pair of tau-leptons. The ratio of the measured cross-section to the Standard Model prediction is mu(tau tau)(VH) = 1.28(-0.29) (+0.30) (stat.) (+0.25)(-0.21) (syst.). This result represents the most accurate measurement of the VH (tau tau) process achieved to date

    Measurement of the H → γ γ and H → ZZ∗ → 4 cross-sections in pp collisions at √s = 13.6 TeV with the ATLAS detector

    Get PDF
    The inclusive Higgs boson production cross section is measured in the di-photon and the Z Z∗ → 4 decay channels using 31.4 and 29.0 fb−1 of pp collision data respectively, collected with the ATLAS detector at a centre of-mass energy of √s = 13.6 TeV. To reduce the model dependence, the measurement in each channel is restricted to a particle-level phase space that closely matches the chan nel’s detector-level kinematic selection, and it is corrected for detector effects. These measured fiducial cross-sections are σfid,γ γ = 76+14 −13 fb, and σfid,4 = 2.80 ± 0.74 fb, in agreement with the corresponding Standard Model predic tions of 67.6±3.7 fb and 3.67±0.19 fb. Assuming Standard Model acceptances and branching fractions for the two chan nels, the fiducial measurements are extrapolated to the full phase space yielding total cross-sections of σ (pp → H) = 67+12 −11 pb and 46±12 pb at 13.6 TeV from the di-photon and Z Z∗ → 4 measurements respectively. The two measure ments are combined into a total cross-section measurement of σ (pp → H) = 58.2±8.7 pb, to be compared with the Stan dard Model prediction of σ (pp → H)SM = 59.9 ± 2.6 p

    Search for non-resonant Higgs boson pair production in final states with leptons, taus, and photons in pp collisions at s \sqrt{s} = 13 TeV with the ATLAS detector

    Get PDF

    Search for pair-production of vector-like quarks in lepton+jets final states containing at least one b-tagged jet using the Run 2 data from the ATLAS experiment

    Get PDF
    A search is presented for the pair-production of heavy vector-like quarks in the lepton+jets final state using 140 fb(-1) of proton-proton collisions at root s = 13 TeV collected with the ATLAS detector. The search is optimised for vector-like top-quarks (T) that decay into a W boson and a b-quark, with one W boson decaying leptonically and the other hadronically. Other vector-like quark flavours and decay modes are also considered. Events are selected with one high transverse-momentum electron or muon, large missing transverse momentum, a large-radius jet identified as a W boson, and multiple small-radius jets, at least one of which is b-tagged. Vector-like T-quarks with 100% branching ratio to Wb are excluded at 95% CL for masses below 1700 GeV. These limits are also applied to vector-like Y-quarks, which decay exclusively into a W boson and a b-quark. Isospin singlets with B(T -> Wb: Ht: Zt ) = 1/2 : 1/4 : 1/4 are excluded for masses below 1360 GeV

    Beam-induced backgrounds measured in the ATLAS detector during local gas injection into the LHC beam vacuum

    Get PDF
    corecore