637 research outputs found

    Evidence for Four-Top Quark Production at the LHC

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    The standard model production of four top quarks is predicted to have a cross section of the order of 12fb. The CMS Collaboration presents new results on this rare production mechanism for Run 2 data collected in 2016 through 2018 at 13 TeV, considering event signatures containing zero to four electrons or muons. This is the first time the all-hadronic channel is investigated in the study of four top quarks, made possible through novel machine learning based data-driven background estimation techniques.Comment: Talk at the 15th International Workshop on Top Quark Physics, Durham, UK, 4-9 September 2022. 7 pages, 1 table, 6 figure

    Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

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    A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe

    MUSiC : a model-unspecific search for new physics in proton-proton collisions at root s=13TeV