1,286 research outputs found

    First observation of Z boson plus two jet production

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    Events with jets produced in association with a Z boson in proton-proton collisions can be used to study distributions sensitive to the vector boson fusion (VBF) process at CERN's Large Hadron Collider. This process is interesting to study because of its similarity to the VBF production of a Higgs boson as well as its sensitivity to new physics via the WWZ triple gauge coupling. Evidence for electroweak Zjj production beyond the 5 level is presented using data collected at a centre-of-mass energy of \sqrt{s} = 8 TeV by the ATLAS experiment in 2012. This constitutes the first observation of a VBF-like process. The detector-corrected cross sections measured in two fi ducial regions are in excellent agreement with the Standard Model expectations and have also been used to constrain anomalous triple gauge couplings. Furthermore, detector-corrected cross sections and diff erential distributions for inclusive Zjj production are presented in di fferent regions of phase space with varying sensitivity to the electroweak Zjj component. In addition, a performance study of the tracking algorithms used in the ATLAS high-level trigger system is presented

    Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

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    This paper presents measurements of the W+μ+νW^+ \rightarrow \mu^+\nu and WμνW^- \rightarrow \mu^-\nu cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

    Measurement of the production of a W boson in association with a charm quark in pp collisions at √s = 7 TeV with the ATLAS detector