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1. Search for long-lived particles decaying in the CMS muon detectors in proton-proton collisions at $\sqrt{s}=13\mathrm{TeV}$

   https://doi.org/10.1103/PhysRevD.110.032007  

   Hayrapetyan, A; Tumasyan, A; Adam, W; Andrejkovic, J W; Bergauer, T; Chatterjee, S; Damanakis, K; Dragicevic, M; Hussain, P S; Jeitler, M; et al (August 2024, Physical Review D)

   A search for long-lived particles (LLPs) decaying in the CMS muon detectors is presented. A data sample of proton-proton collisions at $\sqrt{s}=13\mathrm{TeV}$corresponding to an integrated luminosity of $138{\mathrm{fb}}^{-1}$, recorded at the LHC in 2016–2018, is used. The decays of LLPs are reconstructed as high multiplicity clusters of hits in the muon detectors. In the context of twin Higgs models, the search is sensitive to LLP masses from 0.4 to 55 GeV and a broad range of LLP decay modes, including decays to hadrons, $\tau$leptons, electrons, or photons. No excess of events above the standard model background is observed. The most stringent limits to date from LHC data are set on the branching fraction of the Higgs boson decay to a pair of LLPs with masses below 10 GeV. This search also provides the best limits for various intervals of LLP proper decay length and mass. Finally, this search sets the first limits at the LHC on a dark quantum chromodynamic sector whose particles couple to the Higgs boson through gluon, Higgs boson, photon, vector, and dark-photon portals, and is sensitive to branching fractions of the Higgs boson to dark quarks as low as $2\times {10}^{-3}$. © 2024 CERN, for the CMS Collaboration2024CERN 

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2. Search for a scalar or pseudoscalar dilepton resonance produced in association with a massive vector boson or top quark-antiquark pair in multilepton events at $\sqrt{s}=13\mathrm{TeV}$

   https://doi.org/10.1103/PhysRevD.110.012013  

   Tumasyan, A; Adam, W; Andrejkovic, J W; Bergauer, T; Chatterjee, S; Damanakis, K; Dragicevic, M; Escalante_Del_Valle, A; Hussain, P S; Jeitler, M; et al (July 2024, Physical Review D)

   A search for beyond the standard model spin-0 bosons, $\varphi$, that decay into pairs of electrons, muons, or tau leptons is presented. The search targets the associated production of such bosons with a $W$or $Z$gauge boson, or a top quark-antiquark pair, and uses events with three or four charged leptons, including hadronically decaying tau leptons. The proton-proton collision data set used in the analysis was collected at the LHC from 2016 to 2018 at a center-of-mass energy of 13 TeV, and corresponds to an integrated luminosity of $138{\mathrm{fb}}^{-1}$. The observations are consistent with the predictions from standard model processes. Upper limits are placed on the product of cross sections and branching fractions of such new particles over the mass range of 15 to 350 GeV with scalar, pseudoscalar, or Higgs-boson-like couplings, as well as on the product of coupling parameters and branching fractions. Several model-dependent exclusion limits are also presented. For a Higgs-boson-like $\varphi$model, limits are set on the mixing angle of the Higgs boson with the $\varphi$boson. For the associated production of a $\varphi$boson with a top quark-antiquark pair, limits are set on the coupling to top quarks. Finally, limits are set for the first time on a fermiophilic dilaton-like model with scalar couplings and a fermiophilic axion-like model with pseudoscalar couplings. © 2024 CERN, for the CMS Collaboration2024CERN 

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3. Search for Baryon Number Violation in Top Quark Production and Decay Using Proton-Proton Collisions at $\sqrt{s}=13\mathrm{TeV}$

   https://doi.org/10.1103/PhysRevLett.132.241802  

   Hayrapetyan, A; Tumasyan, A; Adam, W; Andrejkovic, J W; Bergauer, T; Chatterjee, S; Damanakis, K; Dragicevic, M; Hussain, P S; Jeitler, M; et al (June 2024, Physical Review Letters)

   A search is presented for baryon number violating interactions in top quark production and decay. The analysis uses data from proton-proton collisions at a center-of-mass energy of 13 TeV, collected with the CMS detector at the LHC with an integrated luminosity of $138{\mathrm{fb}}^{-1}$. Candidate events are selected by requiring two oppositely charged leptons (electrons or muons) and exactly one jet identified as originating from a bottom quark. Multivariate discriminants are used to separate the signal from the background. No significant deviation from the standard model prediction is observed. Upper limits are placed on the strength of baryon number violating couplings. For the first time the production of single top quarks via baryon number violating interactions is studied. This allows the search to set the most stringent constraints to date on the branching fraction of the top quark decay to a lepton, an up-type quark ( $u$or $c$), and a down-type quark ( $d$, $s$, or $b$). The results improve the previous bounds by 3 to 6 orders of magnitude based on the fermion flavor combination of the baryon number violating interactions. © 2024 CERN, for the CMS Collaboration2024CERN 

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4. Search for bottom-type vectorlike quark pair production in dileptonic and fully hadronic final states in proton-proton collisions at $\sqrt{s}=13\mathrm{TeV}$

   https://doi.org/10.1103/PhysRevD.110.052004  

   Hayrapetyan, A; Tumasyan, A; Adam, W; Andrejkovic, J W; Bergauer, T; Chatterjee, S; Damanakis, K; Dragicevic, M; Hussain, P S; Jeitler, M; et al (September 2024, Physical Review D)

   A search is described for the production of a pair of bottom-type vectorlike quarks ( $B$VLQs) with mass greater than 1000 GeV. Each $B$VLQ decays into a $b$quark and a Higgs boson, a $b$quark and a $Z$boson, or a $t$quark and a $W$boson. This analysis considers both fully hadronic final states and those containing a charged lepton pair from a $Z$boson decay. The products of the $H\to bb$boson decay and of the hadronic $Z$or $W$boson decays can be resolved as two distinct jets or merged into a single jet, so the final states are classified by the number of reconstructed jets. The analysis uses data corresponding to an integrated luminosity of $138{\mathrm{fb}}^{-1}$collected in proton-proton collisions at $\sqrt{s}=13\mathrm{TeV}$with the CMS detector at the LHC from 2016 to 2018. No excess over the expected background is observed. Lower limits are set on the $B$VLQ mass at the 95% confidence level. These depend on the $B$VLQ branching fractions and are 1570 and 1540 GeV for 100% $B\to bH$and 100% $B\to bZ$, respectively. In most cases, the mass limits obtained exceed previous limits by at least 100 GeV. © 2024 CERN, for the CMS Collaboration2024CERN 

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5. Combination of Searches for Resonant Higgs Boson Pair Production Using $pp$ Collisions at $\sqrt{s}=13\mathrm{TeV}$ with the ATLAS Detector

   https://doi.org/10.1103/PhysRevLett.132.231801  

   Aad, G; Aakvaag, E; Abbott, B; Abeling, K; Abicht, N J; Abidi, S H; Aboulhorma, A; Abramowicz, H; Abreu, H; Abulaiti, Y; et al (June 2024, Physical Review Letters)

   A combination of searches for a new resonance decaying into a Higgs boson pair is presented, using up to $139{\mathrm{fb}}^{-1}$of $pp$collision data at $\sqrt{s}=13\mathrm{TeV}$recorded with the ATLAS detector at the LHC. The combination includes searches performed in three decay channels: $b\overline{b}b\overline{b}$, $b\overline{b}{\tau }^{+}{\tau }^{-}$, and $b\overline{b}\gamma \gamma$. No excess above the expected Standard Model background is observed and upper limits are set at the 95% confidence level on the production cross section of Higgs boson pairs originating from the decay of a narrow scalar resonance with mass in the range 251 GeV–5 TeV. The observed (expected) limits are in the range 0.96–600 fb (1.2–390 fb). The limits are interpreted in the type-I two-Higgs-doublet model and the minimal supersymmetric standard model, and constrain parameter space not previously excluded by other searches. © 2024 CERN, for the ATLAS Collaboration2024CERN 

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