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  1. Free, publicly-accessible full text available September 1, 2024
  2. A bstract The first measurement of the top quark pair ( $$ \textrm{t}\overline{\textrm{t}} $$ t t ¯ ) production cross section in proton-proton collisions at $$ \sqrt{s} $$ s = 13 . 6 TeV is presented. Data recorded with the CMS detector at the CERN LHC in Summer 2022, corresponding to an integrated luminosity of 1 . 21 fb − 1 , are analyzed. Events are selected with one or two charged leptons (electrons or muons) and additional jets. A maximum likelihood fit is performed in event categories defined by the number and flavors of the leptons, the number of jets, and the number of jets identified as originating from b quarks. An inclusive $$ \textrm{t}\overline{\textrm{t}} $$ t t ¯ production cross section of 881 ± 23 (stat + syst) ± 20 (lumi) pb is measured, in agreement with the standard model prediction of $$ {924}_{-40}^{+32} $$ 924 − 40 + 32 pb. 
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    Free, publicly-accessible full text available September 1, 2024
  3. A<sc>bstract</sc>

    A search for a charged Higgs boson H±decaying into a heavy neutral Higgs boson H and a W boson is presented. The analysis targets the H decay into a pair of tau leptons with at least one of them decaying hadronically and with an additional electron or muon present in the event. The search is based on proton-proton collision data recorded by the CMS experiment during 2016–2018 at$$ \sqrt{s} $$s= 13 TeV, corresponding to an integrated luminosity of 138 fb1. The data are consistent with standard model background expectations. Upper limits at 95% confidence level are set on the product of the cross section and branching fraction for an H±in the mass range of 300–700 GeV, assuming an H with a mass of 200 GeV. The observed limits range from 0.085 pb for an H±mass of 300 Ge V to 0.019 pb for a mass of 700 GeV. These are the first limits on H±production in the H±HW±decay channel at the LHC.

     
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    Free, publicly-accessible full text available September 1, 2024
  4. A bstract A search for pair production of the supersymmetric partner of the top quark, the top squark, in proton-proton collisions at $$ \sqrt{s} $$ s = 13 TeV is presented in final states containing at least one hadronically decaying tau lepton and large missing transverse momentum. This final state is highly sensitive to scenarios of supersymmetry in which the decay of the top squark to tau leptons is enhanced. The search uses a data sample corresponding to an integrated luminosity of 138 fb − 1 , which was recorded with the CMS detector during 2016–2018. No significant excess is observed with respect to the standard model predictions. Exclusion limits at 95% confidence level on the masses of the top squark and the lightest neutralino are presented under the assumptions of simplified models. The results probe top squark masses up to 1150 GeV for a nearly massless neutralino. This search covers a relatively less explored parameter space in the context of supersymmetry, and the exclusion limit is the most stringent to date for the model considered here. 
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    Free, publicly-accessible full text available July 1, 2024
  5. A bstract A search is presented for vector-like T and B quark-antiquark pairs produced in proton-proton collisions at a center-of-mass energy of 13 TeV. Data were collected by the CMS experiment at the CERN LHC in 2016–2018, with an integrated luminosity of 138 fb − 1 . Events are separated into single-lepton, same-sign charge dilepton, and multi-lepton channels. In the analysis of the single-lepton channel a multilayer neural network and jet identification techniques are employed to select signal events, while the same-sign dilepton and multilepton channels rely on the high-energy signature of the signal to distinguish it from standard model backgrounds. The data are consistent with standard model background predictions, and the production of vector-like quark pairs is excluded at 95% confidence level for T quark masses up to 1.54 TeV and B quark masses up to 1.56 TeV, depending on the branching fractions assumed, with maximal sensitivity to decay modes that include multiple top quarks. The limits obtained in this search are the strongest limits to date for $$ \textrm{T}\overline{\textrm{T}} $$ T T ¯ production, excluding masses below 1.48 TeV for all decays to third generation quarks, and are the strongest limits to date for $$ \textrm{B}\overline{\textrm{B}} $$ B B ¯ production with B quark decays to tW. 
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    Free, publicly-accessible full text available July 1, 2024
  6. A bstract A search for the pair production of the lightest supersymmetric partner of the top quark, the top squark ( $$ {\overset{\sim }{\textrm{t}}}_1 $$ t ~ 1 ), is presented. The search targets the four-body decay of the $$ {\overset{\sim }{\textrm{t}}}_1 $$ t ~ 1 , which is preferred when the mass difference between the top squark and the lightest supersymmetric particle is smaller than the mass of the W boson. This decay mode consists of a bottom quark, two other fermions, and the lightest neutralino ( $$ {\overset{\sim }{\chi}}_1^0 $$ χ ~ 1 0 ), which is assumed to be the lightest supersymmetric particle. The data correspond to an integrated luminosity of 138 fb − 1 of proton-proton collisions at a center-of-mass energy of 13 TeV collected by the CMS experiment at the CERN LHC. Events are selected using the presence of a high-momentum jet, an electron or muon with low transverse momentum, and a significant missing transverse momentum. The signal is selected based on a multivariate approach that is optimized for the difference between m ( $$ {\overset{\sim }{\textrm{t}}}_1 $$ t ~ 1 ) and m ( $$ {\overset{\sim }{\chi}}_1^0 $$ χ ~ 1 0 ). The contribution from leading background processes is estimated from data. No significant excess is observed above the expectation from standard model processes. The results of this search exclude top squarks at 95% confidence level for masses up to 480 and 700 GeV for m ( $$ {\overset{\sim }{\textrm{t}}}_1 $$ t ~ 1 ) − m ( $$ {\overset{\sim }{\chi}}_1^0 $$ χ ~ 1 0 ) = 10 and 80 GeV, respectively. 
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    Free, publicly-accessible full text available June 1, 2024
  7. A bstract The first search for nonresonant production of Higgs boson pairs (HH) with one H decaying into four leptons and the other into a pair of b quarks is presented, using proton-proton collisions recorded at a center-of-mass energy of $$ \sqrt{s} $$ s = 13 TeV by the CMS experiment. The analyzed data correspond to an integrated luminosity of 138 fb − 1 . A 95% confidence level upper limit of 32.4 is set on the signal strength modifier μ , defined as the ratio of the observed HH production rate in the $$ \textrm{HH}\to {\textrm{ZZ}}^{\ast}\textrm{b}\overline{\textrm{b}}\to 4\ell \textrm{b}\overline{\textrm{b}} $$ HH → ZZ ∗ b b ¯ → 4 ℓ b b ¯ decay channel to the standard model (SM) expectation. Possible modifications of the H trilinear coupling λ HHH with respect to the SM value are investigated. The coupling modifier κ λ , defined as λ HHH divided by its SM prediction, is constrained to be within the observed (expected) range − 8 . 8 ( − 9 . 8) < κ λ < 13 . 4 (15 . 0) at 95% confidence level. 
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    Free, publicly-accessible full text available June 1, 2024