| 1. |
- Bertoli, Gabriele, et al.
(författare)
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A strategy for a general search for new phenomena using data-derived signal regions and its application within the ATLAS experiment
- 2019
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 79:2
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes a strategy for a general search used by the ATLAS Collaboration to find potential indications of new physics. Events are classified according to their final state into many event classes. For each event class an automated search algorithm tests whether the data are compatible with the Monte Carlo simulated expectation in several distributions sensitive to the effects of new physics. The significance of a deviation is quantified using pseudo-experiments. A data selection with a significant deviation defines a signal region for a dedicated follow-up analysis with an improved background expectation. The analysis of the data-derived signal regions on a new dataset allows a statistical interpretation without the large look-elsewhere effect. The sensitivity of the approach is discussed using Standard Model processes and benchmark signals of new physics. As an example, results are shown for 3.2fb-1 of proton-proton collision data at a centre-of-mass energy of 13TeV collected with the ATLAS detector at the LHC in 2015, in which more than 700 event classes and more than 105 regions have been analysed. No significant deviations are found and consequently no data-derived signal regions for a follow-up analysis have been defined.
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| 2. |
- Bertoli, Gabriele, et al.
(författare)
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Search for invisible Higgs boson decays in vector boson fusion at root s=13 TeV with the ATLAS detector
- 2019
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 793, s. 499-519
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Tidskriftsartikel (refereegranskat)abstract
- We report a search for Higgs bosons that are produced via vector boson fusion and subsequently decay into invisible particles. The experimental signature is an energetic jet pair with invariant mass of O(1) TeVand O(100) GeVmissing transverse momentum. The analysis uses 36.1 fb(-1) of pp collision data at root s = 13 TeV recorded by the ATLAS detector at the LHC. In the signal region the 2252 observed events are consistent with the background estimation. Assuming a 125 GeV scalar particle with Standard Model cross sections, the upper limit on the branching fraction of the Higgs boson decay into invisible particles is 0.37 at 95% confidence level where 0.28 was expected. This limit is interpreted in Higgs portal models to set bounds on the wimp-nucleon scattering cross section. We also consider invisible decays of additional scalar bosons with masses up to 3 TeV for which the upper limits on the cross section times branching fraction are in the range of 0.3-1.7 pb.
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| 3. |
- Milstead, David A., et al.
(författare)
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Search for heavy Majorana or Dirac neutrinos and right-handed W gauge bosons in final states with two charged leptons and two jets at √s=13 TeV with the ATLAS detector
- 2019
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Ingår i: Journal of High Energy Physics. - : Springer Nature. - 1029-8479 .- 1126-6708. ; 2019:1
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Tidskriftsartikel (refereegranskat)abstract
- A search for heavy right-handed Majorana or Dirac neutrinos N R and heavy right-handed gauge bosons W R is performed in events with a pair of energetic electrons or muons, with the same or opposite electric charge, and two energetic jets. The events are selected from pp collision data with an integrated luminosity of 36.1 fb −1 collected by the ATLAS detector at s=13 TeV. No significant deviations from the Standard Model are observed. The results are interpreted within the theoretical framework of a left-right symmetric model and lower limits are set on masses in the heavy right-handed W boson and neutrino mass plane. The excluded region extends to mRR=4.7 TeV for both Majorana and Dirac N R neutrinos. © 2019, The Author(s).
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