14 research outputs found

    Measurement of the W±ZW^{\pm}Z boson pair-production cross section in pppp collisions at s=13\sqrt{s}=13 TeV with the ATLAS Detector

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    The production of W±ZW^{\pm}Z events in proton--proton collisions at a centre-of-mass energy of 13 TeV is measured with the ATLAS detector at the LHC. The collected data correspond to an integrated luminosity of 3.2 fb1^{-1}. The W±ZW^{\pm}Z candidates are reconstructed using leptonic decays of the gauge bosons into electrons or muons. The measured inclusive cross section in the detector fiducial region for leptonic decay modes is σW±Zνfid.=63.2±3.2\sigma_{W^\pm Z \rightarrow \ell^{'} \nu \ell \ell}^{\textrm{fid.}} = 63.2 \pm 3.2 (stat.) ±2.6\pm 2.6 (sys.) ±1.5\pm 1.5 (lumi.) fb. In comparison, the next-to-leading-order Standard Model prediction is 53.42.8+3.653.4^{+3.6}_{-2.8} fb. The extrapolation of the measurement from the fiducial to the total phase space yields σW±Ztot.=50.6±2.6\sigma_{W^{\pm}Z}^{\textrm{tot.}} = 50.6 \pm 2.6 (stat.) ±2.0\pm 2.0 (sys.) ±0.9\pm 0.9 (th.) ±1.2\pm 1.2 (lumi.) pb, in agreement with a recent next-to-next-to-leading-order calculation of 48.21.0+1.148.2^{+1.1}_{-1.0} pb. The cross section as a function of jet multiplicity is also measured, together with the charge-dependent W+ZW^+Z and WZW^-Z cross sections and their ratio

    Measurement of differential J/ψJ/\psi production cross-sections and forward-backward ratio in p+Pb collisions with the ATLAS detector

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    Measurements of differential cross-sections for J/ψJ/\psi production in p+Pb collisions at sNN\sqrt{s_{NN}} = 5.02 TeV at the LHC with the ATLAS detector are presented. The data set used corresponds to an integrated luminosity of 28.1 nb1^{-1}. The J/ψJ/\psi mesons are reconstructed in the dimuon decay channel over the transverse momentum range 8<pT<308<p_{\mathrm{T}}<30 GeV and over the center-of-mass rapidity range 2.87<y<1.94-2.87<y^{*}<1.94. Prompt J/ψJ/\psi are separated from J/ψJ/\psi resulting from bb-hadron decays through an analysis of the distance between the J/ψJ/\psi decay vertex and the event primary vertex. The differential cross-section for production of nonprompt J/ψJ/\psi is compared to a FONLL calculation that does not include nuclear effects. Forward-backward production ratios are presented and compared to theoretical predictions. These results constrain the kinematic dependence of nuclear modifications of charmonium and bb-quark production in p+Pb collisions

    Search for Scalar Diphoton Resonances in the Mass Range 6560065-600 GeV with the ATLAS Detector in pppp Collision Data at s\sqrt{s} = 8 TeVTeV

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    A search for scalar particles decaying via narrow resonances into two photons in the mass range 65–600 GeV is performed using 20.3fb120.3\text{}\text{}{\mathrm{fb}}^{-1} of s=8TeV\sqrt{s}=8\text{}\text{}\mathrm{TeV} pppp collision data collected with the ATLAS detector at the Large Hadron Collider. The recently discovered Higgs boson is treated as a background. No significant evidence for an additional signal is observed. The results are presented as limits at the 95% confidence level on the production cross section of a scalar boson times branching ratio into two photons, in a fiducial volume where the reconstruction efficiency is approximately independent of the event topology. The upper limits set extend over a considerably wider mass range than previous searches

    Search for Scalar-Charm pair production in pp collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

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    The results of a dedicated search for pair production of scalar partners of charm quarks are reported. The search is based on an integrated luminosity of 20.3 fb1^{-1} of pp collisions at s=8\sqrt{s}=8 TeV recorded with the ATLAS detector at the LHC. The search is performed using events with large missing transverse momentum and at least two jets, where the two leading jets are each tagged as originating from c-quarks. Events containing isolated electrons or muons are vetoed. In an R-parity-conserving minimal supersymmetric scenario in which a single scalar-charm state is kinematically accessible, and where it decays exclusively into a charm quark and a neutralino, 95% confidence-level upper limits are obtained in the scalar-charm-neutralino mass plane such that, for neutralino masses below 200 GeV, scalar-charm masses up to 490 GeV are excluded

    Search for pair-produced higgsinos decaying via Higgs or ZZ bosons to final states containing a pair of photons and a pair of bb-jets with the ATLAS detector

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    A detailed map of Higgs boson interactions by the ATLAS experiment ten years after the discovery

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    Search for Higgs and ZZ Boson Decays to J/ψγJ/\psi\gamma and Υ(nS)γ\Upsilon(nS)\gamma with the ATLAS Detector

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    A search for the decays of the Higgs and ZZ bosons to J/ψγJ/\psi\gamma and Υ(nS)γ\Upsilon(nS)\gamma (n=1,2,3n=1,2,3) is performed with pppp collision data samples corresponding to integrated luminosities of up to 20.3fb120.3\mathrm{fb}^{-1} collected at s=8TeV\sqrt{s}=8\mathrm{TeV} with the ATLAS detector at the CERN Large Hadron Collider. No significant excess of events is observed above expected backgrounds and 95% CL upper limits are placed on the branching fractions. In the J/ψγJ/\psi\gamma final state the limits are 1.5×1031.5\times10^{-3} and 2.6×1062.6\times10^{-6} for the Higgs and ZZ bosons, respectively, while in the Υ(1S,2S,3S)γ\Upsilon(1S,2S,3S)\,\gamma final states the limits are (1.3,1.9,1.3)×103(1.3,1.9,1.3)\times10^{-3} and (3.4,6.5,5.4)×106(3.4,6.5,5.4)\times10^{-6}, respectively

    Search for Higgs and Z Boson Decays to J/ψγJ/\psi\gamma and Υ(nS)γ\Upsilon(nS)\gamma with the ATLAS Detector

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    A search for the decays of the Higgs and Z bosons to J/ψγ and ϒ(nS)γ (n=1,2,3) is performed with pp collision data samples corresponding to integrated luminosities of up to 20.3 fb-1 collected at s=8 TeV with the ATLAS detector at the CERN Large Hadron Collider. No significant excess of events is observed above expected backgrounds and 95% C.L. upper limits are placed on the branching fractions. In the J/ψγ final state the limits are 1.5×10-3 and 2.6×10-6 for the Higgs and Z boson decays, respectively, while in the ϒ(1S,2S,3S)γ final states the limits are (1.3,1.9,1.3)×10-3 and (3.4,6.5,5.4)×10-6, respectively
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