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  1. A<sc>bstract</sc>

    A search for the central exclusive production of top quark-antiquark pairs ($$ \textrm{t}\overline{\textrm{t}} $$tt¯) is performed for the first time using proton-tagged events in proton-proton collisions at the LHC at a centre-of-mass energy of 13 TeV. The data correspond to an integrated luminosity of 29.4 fb1. The$$ \textrm{t}\overline{\textrm{t}} $$tt¯decay products are reconstructed using the central CMS detector, while forward protons are measured in the CMS-TOTEM precision proton spectrometer. An observed (expected) upper bound on the production cross section of 0.59 (1.14) pb is set at 95% confidence level, for collisions of protons with fractional momentum losses between 2 and 20%.

     
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    Free, publicly-accessible full text available June 1, 2025
  2. A<sc>bstract</sc>

    A search for a new boson X is presented using CERN LHC proton-proton collision data collected by the CMS experiment at$$ \sqrt{s} $$s= 13 TeV in 2016–2018, and corresponding to an integrated luminosity of 138 fb1. The resonance X decays into either a pair of Higgs bosons HH of mass 125 GeV or an H and a new spin-0 boson Y. One H subsequently decays to a pair of photons, and the second H or Y, to a pair of bottom quarks. The explored mass ranges of X are 260–1000 GeV and 300–1000 GeV, for decays to HH and to HY, respectively, with the Y mass range being 90–800 GeV. For a spin-0 X hypothesis, the 95% confidence level upper limit on the product of its production cross section and decay branching fraction is observed to be within 0.90–0.04 fb, depending on the masses of X and Y. The largest deviation from the background-only hypothesis with a local (global) significance of 3.8 (below 2.8) standard deviations is observed for X and Y masses of 650 and 90 GeV, respectively. The limits are interpreted using several models of new physics.

     
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    Free, publicly-accessible full text available May 1, 2025
  3. A<sc>bstract</sc>

    A search for supersymmetry is presented in events with a single charged lepton, electron or muon, and multiple hadronic jets. The data correspond to an integrated luminosity of 138 fb1of proton-proton collisions at a center-of-mass energy of 13 TeV, recorded by the CMS experiment at the CERN LHC. The search targets gluino pair production, where the gluinos decay into final states with the lightest supersymmetric particle (LSP) and either a top quark-antiquark ($$ \textrm{t}\overline{\textrm{t}} $$tt¯) pair, or a light-flavor quark-antiquark ($$ \textrm{q}\overline{\textrm{q}} $$qq¯) pair and a virtual or on-shell W boson. The main backgrounds,$$ \textrm{t}\overline{\textrm{t}} $$tt¯pair and W+jets production, are suppressed by requirements on the azimuthal angle between the momenta of the lepton and of its reconstructed parent W boson candidate, and by top quark and W boson identification based on a machine-learning technique. The number of observed events is consistent with the expectations from standard model processes. Limits are evaluated on supersymmetric particle masses in the context of two simplified models of gluino pair production. Exclusions for gluino masses reach up to 2120 (2050) GeV at 95% confidence level for a model with gluino decay to a$$ \textrm{t}\overline{\textrm{t}} $$tt¯pair (a$$ \textrm{q}\overline{\textrm{q}} $$qq¯pair and a W boson) and the LSP. For the same models, limits on the mass of the LSP reach up to 1250 (1070) GeV.

     
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