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A description is presented of the algorithms used to reconstruct energy deposited in the CMS hadron calorimeter during Run 2 (2015–2018) of the LHC. During Run 2, the characteristic bunch-crossing spacing for proton-proton collisions was 25 ns, which resulted in overlapping signals from adjacent crossings. The energy corresponding to a particular bunch crossing of interest is estimated using the known pulse shapes of energy depositions in the calorimeter, which are measured as functions of both energy and time. A variety of algorithms were developed to mitigate the effects of adjacent bunch crossings on local energy reconstruction in the hadron calorimeter in Run 2, and their performance is compared.

 

A search for high-mass dimuon resonance production in association with one or more b quark jets is presented. The study uses proton-proton collision data collected with the CMS detector at the LHC corresponding to an integrated luminosity of 138 fb⁻¹at a center-of-mass energy of 13 TeV. Model-independent limits are derived on the number of signal events with exactly one or more than one b quark jet. Results are also interpreted in a lepton-flavor-universal model with Z′ boson couplings to a bb quark pair (g_b), an sb quark pair (g_bδ_bs), and any same-flavor charged lepton (g_ℓ) or neutrino pair (g_ν), with|g_ν|=|g_ℓ|. For a Z′ boson with a mass$$ {m}_{{\textrm{Z}}^{\prime }} $$$m_{Z^{\prime }}$= 350 GeV (2 TeV) and|δ_bs|< 0.25, the majority of the parameter space with 0.0057 <|g_ℓ|< 0.35 (0.25 <|g_ℓ|< 0.43) and 0.0079 < |g_b| < 0.46 (0.34 < |g_b| < 0.57) is excluded at 95% confidence level. Finally, constraints are set on a Z′ model with parameters consistent with low-energy b → sℓℓmeasurements. In this scenario, most of the allowed parameter space is excluded for a Z′ boson with 350 <$$ {m}_{{\textrm{Z}}^{\prime }} $$$m_{Z^{\prime }}$< 500 GeV, while the constraints are less stringent for higher$$ {m}_{{\textrm{Z}}^{\prime }} $$$m_{Z^{\prime }}$hypotheses. This is the first dedicated search at the LHC for a high-mass dimuon resonance produced in association with multiple b quark jets, and the constraints obtained on models with this signature are the most stringent to date.

 

Abstract The Precision Proton Spectrometer (PPS) of the CMS and TOTEM experiments collected 107.7 fb -1 in proton-proton (pp) collisions at the LHC at 13 TeV (Run 2). This paper describes the key features of the PPS alignment and optics calibrations, the proton reconstruction procedure, as well as the detector efficiency and the performance of the PPS simulation. The reconstruction and simulation are validated using a sample of (semi)exclusive dilepton events. The performance of PPS has proven the feasibility of continuously operating a near-beam proton spectrometer at a high luminosity hadron collider. 

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. 

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 fb⁻¹of 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 ($$ \textrm{t}\overline{\textrm{t}} $$$t\overline{t}$) pair, or a light-flavor quark-antiquark ($$ \textrm{q}\overline{\textrm{q}} $$$q\overline{q}$) pair and a virtual or on-shell W boson. The main backgrounds,$$ \textrm{t}\overline{\textrm{t}} $$$t\overline{t}$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$$ \textrm{t}\overline{\textrm{t}} $$$t\overline{t}$pair (a$$ \textrm{q}\overline{\textrm{q}} $$$q\overline{q}$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.