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  1. Free, publicly-accessible full text available November 1, 2024
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  5. A<sc>bstract</sc>

    Results are presented from a search for CP violation in top quark pair production, using proton-proton collisions at a center-of-mass energy of 13 TeV. The data used for this analysis consist of final states with two charged leptons collected by the CMS experiment, and correspond to an integrated luminosity of 35.9 fb1. The search uses two observables,$$ \mathcal{O} $$O1and$$ \mathcal{O} $$O3, which are Lorentz scalars. The observable$$ \mathcal{O} $$O1is constructed from the four-momenta of the charged leptons and the reconstructed top quarks, while$$ \mathcal{O} $$O3consists of the four-momenta of the charged leptons and the b quarks originating from the top quarks. Asymmetries in these observables are sensitive to CP violation, and their measurement is used to determine the chromoelectric dipole moment of the top quark. The results are consistent with the expectation from the standard model.

     
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  6. Abstract

    The double differential cross sections of the Drell–Yan lepton pair ($$\ell ^+\ell ^-$$+-, dielectron or dimuon) production are measured as functions of the invariant mass$$m_{\ell \ell }$$m, transverse momentum$$p_{\textrm{T}} (\ell \ell )$$pT(), and$$\varphi ^{*}_{\eta }$$φη. The$$\varphi ^{*}_{\eta }$$φηobservable, derived from angular measurements of the leptons and highly correlated with$$p_{\textrm{T}} (\ell \ell )$$pT(), is used to probe the low-$$p_{\textrm{T}} (\ell \ell )$$pT()region in a complementary way. Dilepton masses up to 1$$\,\text {Te\hspace{-.08em}V}$$TeVare investigated. Additionally, a measurement is performed requiring at least one jet in the final state. To benefit from partial cancellation of the systematic uncertainty, the ratios of the differential cross sections for various$$m_{\ell \ell }$$mranges to those in the Z mass peak interval are presented. The collected data correspond to an integrated luminosity of 36.3$$\,\text {fb}^{-1}$$fb-1of proton–proton collisions recorded with the CMS detector at the LHC at a centre-of-mass energy of 13$$\,\text {Te\hspace{-.08em}V}$$TeV. Measurements are compared with predictions based on perturbative quantum chromodynamics, including soft-gluon resummation.

     
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  7. Abstract

    Measurements of the associated production of a W boson and a charm ($${\text {c}}$$c) quark in proton–proton collisions at a centre-of-mass energy of 8$$\,\text {TeV}$$TeVare reported. The analysis uses a data sample corresponding to a total integrated luminosity of 19.7$$\,\text {fb}^{-1}$$fb-1collected by the CMS detector at the LHC. The W bosons are identified through their leptonic decays to an electron or a muon, and a neutrino. Charm quark jets are selected using distinctive signatures of charm hadron decays. The product of the cross section and branching fraction$$\sigma (\text {p}\text {p}\rightarrow \text {W}+ {\text {c}}+ \text {X}) {\mathcal {B}}(\text {W}\rightarrow \ell \upnu )$$σ(ppW+c+X)B(Wν), where$$\ell = \text {e}$$=eor$$\upmu $$μ, and the cross section ratio$$\sigma (\text {p}\text {p}\rightarrow {{\text {W}}^{+} + \bar{{\text {c}}} + \text {X}}) / \sigma (\text {p}\text {p}\rightarrow {{\text {W}}^{-} + {\text {c}}+ \text {X}})$$σ(ppW++c¯+X)/σ(ppW-+c+X)are measured in a fiducial volume and differentially as functions of the pseudorapidity and of the transverse momentum of the lepton from the W boson decay. The results are compared with theoretical predictions. The impact of these measurements on the determination of the strange quark distribution is assessed.

     
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  8. A bstract A search for physics beyond the standard model (SM) in final states with an electron or muon and missing transverse momentum is presented. The analysis uses data from proton-proton collisions at a centre-of-mass energy of 13 TeV, collected with the CMS detector at the LHC in 2016–2018 and corresponding to an integrated luminosity of 138 fb − 1 . No significant deviation from the SM prediction is observed. Model-independent limits are set on the production cross section of W’ bosons decaying into lepton-plus-neutrino final states. Within the framework of the sequential standard model, with the combined results from the electron and muon decay channels a W’ boson with mass less than 5.7 TeV is excluded at 95% confidence level. Results on a SM precision test, the determination of the oblique electroweak W parameter, are presented using LHC data for the first time. These results together with those from the direct W’ resonance search are used to extend existing constraints on composite Higgs scenarios. This is the first experimental exclusion on compositeness parameters using results from LHC data other than Higgs boson measurements. 
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