Abstract The standard model (SM) production of four top quarks ($$\text {t} {}{\overline{\text {t}}} \text {t} {}{\overline{\text {t}}} $$ tt¯tt¯ ) in proton–proton collisions is studied by the CMS ...Collaboration. The data sample, collected during the 2016–2018 data taking of the LHC, corresponds to an integrated luminosity of 137$$\,\text {fb}^{-1}$$ fb-1 at a center-of-mass energy of 13$$\,\text {TeV}$$ TeV . The events are required to contain two same-sign charged leptons (electrons or muons) or at least three leptons, and jets. The observed and expected significances for the $$\text {t} {}{\overline{\text {t}}} \text {t} {}{\overline{\text {t}}} $$ tt¯tt¯ signal are respectively 2.6 and 2.7 standard deviations, and the $$\text {t} {}{\overline{\text {t}}} \text {t} {}{\overline{\text {t}}} $$ tt¯tt¯ cross section is measured to be $$12.6^{+5.8}_{-5.2}\,\text {fb} $$ 12.6-5.2+5.8fb . The results are used to constrain the Yukawa coupling of the top quark to the Higgs boson, $$y_{\text {t}}$$ yt , yielding a limit of $$|y_{\text {t}}/y_{\text {t}}^{\mathrm {SM}} | < 1.7$$ |yt/ytSM|<1.7 at $$95\%$$ 95% confidence level, where $$y_{\text {t}}^{\mathrm {SM}}$$ ytSM is the SM value of $$y_{\text {t}}$$ yt . They are also used to constrain the oblique parameter of the Higgs boson in an effective field theory framework, $$\hat{H}<0.12$$ H^<0.12 . Limits are set on the production of a heavy scalar or pseudoscalar boson in Type-II two-Higgs-doublet and simplified dark matter models, with exclusion limits reaching 350–470$$\,\text {GeV}$$ GeV and 350–550$$\,\text {GeV}$$ GeV for scalar and pseudoscalar bosons, respectively. Upper bounds are also set on couplings of the top quark to new light particles.
Abstract A search for $$\text {W}\text {W}$$ WW production from double-parton scattering processes using same-charge electron-muon and dimuon events is reported, based on proton-proton collision data ...collected at a center-of-mass energy of $$13\,\text {TeV} $$ 13TeV . The analyzed data set corresponds to an integrated luminosity of $$77.4{\,\text {fb}^{-1}} $$ 77.4fb-1 , collected using the CMS detector at the LHC in 2016 and 2017. Multivariate classifiers are used to discriminate between the signal and the dominant background processes. A maximum likelihood fit is performed to extract the signal cross section. This leads to the first evidence for $$\text {W}\text {W}$$ WW production via double-parton scattering, with a significance of 3.9 standard deviations. The measured inclusive cross section is $$1.41\pm 0.28\,\text {(stat)} \pm 0.28\,\text {(syst)} \,\text {pb} $$ 1.41±0.28(stat)±0.28(syst)pb .
Abstract Two related searches for phenomena beyond the standard model (BSM) are performed using events with hadronic jets and significant transverse momentum imbalance. The results are based on a ...sample of proton–proton collisions at a center-of-mass energy of $$13\,\text {Te}\text {V} $$ 13Te , collected by the CMS experiment at the LHC in 2016–2018 and corresponding to an integrated luminosity of 137$$\,\text {fb}^{-1}$$ fb-1 . The first search is inclusive, based on signal regions defined by the hadronic energy in the event, the jet multiplicity, the number of jets identified as originating from bottom quarks, and the value of the kinematic variable $$M_{\mathrm {T2}}$$ MT2 for events with at least two jets. For events with exactly one jet, the transverse momentum of the jet is used instead. The second search looks in addition for disappearing tracks produced by BSM long-lived charged particles that decay within the volume of the tracking detector. No excess event yield is observed above the predicted standard model background. This is used to constrain a range of BSM models that predict the following: the pair production of gluinos and squarks in the context of supersymmetry models conserving R-parity, with or without intermediate long-lived charginos produced in the decay chain; the resonant production of a colored scalar state decaying to a massive Dirac fermion and a quark; or the pair production of scalar and vector leptoquarks each decaying to a neutrino and a top, bottom, or light-flavor quark. In most of the cases, the results obtained are the most stringent constraints to date.
Abstract A measurement is presented of electroweak (EW) production of a $$\mathrm{W} $$ W boson in association with two jets in proton–proton collisions at $$\sqrt{s}=13\,\text {Te}\text {V} $$ ...s=13Te . The data sample was recorded by the CMS Collaboration at the LHC and corresponds to an integrated luminosity of 35.9$$\,\text {fb}^{-1}$$ fb-1 . The measurement is performed for the $$\ell \nu $$ ℓν jj final state (with $$\ell \nu $$ ℓν indicating a lepton–neutrino pair, and j representing the quarks produced in the hard interaction) in a kinematic region defined by invariant mass $$m_\mathrm {jj} >120\,\text {Ge}\text {V} $$ mjj>120Ge and transverse momenta $$p_\mathrm {T j} > 25\,\text {Ge}\text {V} $$ pTj>25Ge . The cross section of the process is measured in the electron and muon channels yielding $$\sigma _\mathrm {EW}(\mathrm{W} \mathrm {jj})= 6.23 \pm 0.12 \,\text {(stat)} \pm 0.61 \,\text {(syst)} \,\text {pb} $$ σEW(Wjj)=6.23±0.12(stat)±0.61(syst)pb per channel, in agreement with leading-order standard model predictions. The additional hadronic activity of events in a signal-enriched region is studied, and the measurements are compared with predictions. The final state is also used to perform a search for anomalous trilinear gauge couplings. Limits on anomalous trilinear gauge couplings associated with dimension-six operators are given in the framework of an effective field theory. The corresponding 95% confidence level intervals are $$-2.3< c_{{\mathrm{W} \mathrm{W} \mathrm{W}}}/\varLambda ^2 < 2.5\,\text {Te}\text {V} ^{-2}$$ -2.3<cWWW/Λ2<2.5Te-2 , $$-8.8< c_{\mathrm{W}}/\varLambda ^2 < 16\,\text {Te}\text {V} ^{-2}$$ -8.8<cW/Λ2<16Te-2 , and $$-45< c_{\mathrm{B}}/\varLambda ^2 < 46\,\text {Te}\text {V} ^{-2}$$ -45<cB/Λ2<46Te-2 . These results are combined with the CMS EW $$\mathrm{Zjj} $$ Zjj analysis, yielding the constraint on the $$c_{{\mathrm{W} \mathrm{W} \mathrm{W}}}$$ cWWW coupling: $$-1.8< c_{{\mathrm{W} \mathrm{W} \mathrm{W}}}/\varLambda ^2 < 2.0\,\text {Te}\text {V} ^{-2}$$ -1.8<cWWW/Λ2<2.0Te-2 .
Abstract A search for new physics in top quark production is performed in proton-proton collisions at $$13\,\text {TeV} $$ 13TeV . The data set corresponds to an integrated luminosity of ...$$35.9{\,\text {fb}^{-1}} $$ 35.9fb-1 collected in 2016 with the CMS detector. Events with two opposite-sign isolated leptons (electrons or muons), and $$\mathrm{b}$$ b quark jets in the final state are selected. The search is sensitive to new physics in top quark pair production and in single top quark production in association with a $$\mathrm{W}$$ W boson. No significant deviation from the standard model expectation is observed. Results are interpreted in the framework of effective field theory and constraints on the relevant effective couplings are set, one at a time, using a dedicated multivariate analysis. This analysis differs from previous searches for new physics in the top quark sector by explicitly separating $$\mathrm{t}\mathrm{W}$$ tW from $$\mathrm{t}{\bar{\mathrm{t}}}$$ tt¯ events and exploiting the specific sensitivity of the $$\mathrm{t}\mathrm{W}$$ tW process to new physics.
Abstract The average total energy as well as its hadronic and electromagnetic components are measured with the CMS detector at pseudorapidities $$-6.6<\eta <-5.2$$ -6.6<η<-5.2 in proton-proton ...collisions at a centre-of-mass energy $$\sqrt{s}=13\,\text {TeV} $$ s=13TeV . The results are presented as a function of the charged particle multiplicity in the region $$|\eta |<2$$ |η|<2 . This measurement is sensitive to correlations induced by the underlying event structure over a very wide pseudorapidity region. The predictions of Monte Carlo event generators commonly used in collider experiments and ultra-high energy cosmic ray physics are compared to the data. All generators considered overestimate the fraction of energy going into hadrons.
Abstract A measurement for inclusive 2- and 3-jet events of the azimuthal correlation between the two jets with the largest transverse momenta, $$\varDelta \phi _{12}$$ Δϕ12 , is presented. The ...measurement considers events where the two leading jets are nearly collinear (“back-to-back”) in the transverse plane and is performed for several ranges of the leading jet transverse momentum. Proton-proton collision data collected with the CMS experiment at a center-of-mass energy of $$13\,\text {Te}\text {V} $$ 13Te and corresponding to an integrated luminosity of $$35.9{\,\text {fb}^{-1}} $$ 35.9fb-1 are used. Predictions based on calculations using matrix elements at leading-order and next-to-leading-order accuracy in perturbative quantum chromodynamics supplemented with leading-log parton showers and hadronization are generally in agreement with the measurements. Discrepancies between the measurement and theoretical predictions are as large as 15%, mainly in the region $$177^\circ< \varDelta \phi _{12} < 180^\circ $$ 177∘<Δϕ12<180∘ . The 2- and 3-jet measurements are not simultaneously described by any of models.
Abstract A search is presented for a heavy pseudoscalar boson $$\text {A}$$ A decaying to a Z boson and a Higgs boson with mass of 125$$\,\text {GeV}$$ GeV . In the final state considered, the Higgs ...boson decays to a bottom quark and antiquark, and the Z boson decays either into a pair of electrons, muons, or neutrinos. The analysis is performed using a data sample corresponding to an integrated luminosity of 35.9$$\,\text {fb}^{-1}$$ fb-1 collected in 2016 by the CMS experiment at the LHC from proton–proton collisions at a center-of-mass energy of 13$$\,\text {Te}\text {V}$$ Te . The data are found to be consistent with the background expectations. Exclusion limits are set in the context of two-Higgs-doublet models in the $$\text {A}$$ A boson mass range between 225 and 1000$$\,\text {GeV}$$ GeV .
Abstract Exclusive $${{{\uprho _{}^{}} _{}^{}}{{\left( {770}\right) }{}_{}^{}}} ^{0}$$ ρ7700 photoproduction is measured for the first time in ultraperipheral pPb collisions at $$\sqrt{\smash ...b{s_{_{\mathrm {NN}}} = 5.02\,\text {Te}\text {V} $$ sNN=5.02Te with the CMS detector. The cross section $$\sigma ({\upgamma _{}^{}} \mathrm{p}\rightarrow {{{\uprho _{}^{}} _{}^{}}{{\left( {770}\right) }{}_{}^{}}} ^{0}\mathrm{p})$$ σ(γp→ρ7700p) is $$11.0 \pm 1.4\,\text {(stat)} \pm 1.0\,\text {(syst)} $$ 11.0±1.4(stat)±1.0(syst) $$\mu $$ μ b at $$\langle W_{{\upgamma _{}^{}} \mathrm{p}}\rangle = 92.6\,\text {Ge}\text {V} $$ ⟨Wγp⟩=92.6Ge for photon–proton centre-of-mass energies $$W_{{\upgamma _{}^{}} \mathrm{p}}$$ Wγp between 29 and $$213\,\text {Ge}\text {V} $$ 213Ge . The differential cross section $$\mathrm {d}\sigma /\mathrm {d}|t |$$ dσ/d|t| is measured in the interval $$0.025< |t | < 1\,\text {Ge}\text {V} ^{2}$$ 0.025<|t|<1Ge2 as a function of $$W_{{\upgamma _{}^{}} \mathrm{p}}$$ Wγp , where t is the squared four-momentum transfer at the proton vertex. The results are compared with previous measurements and theoretical predictions. The measured cross section $$\sigma ({\upgamma _{}^{}} \mathrm{p}\rightarrow {{{\uprho _{}^{}} _{}^{}}{{\left( {770}\right) }{}_{}^{}}} ^{0}\mathrm{p})$$ σ(γp→ρ7700p) has a power-law dependence on the photon–proton centre-of-mass, consistent with electron–proton collision measurements performed at HERA. The $$W_{{\upgamma _{}^{}} \mathrm{p}}$$ Wγp dependence of the exponential slope of the differential cross section $$\mathrm {d}\sigma /\mathrm {d}|t |$$ dσ/d|t| is also measured.
Abstract A top quark mass measurement is performed using $$35.9{\,\text {fb}^{-1}} $$ 35.9fb-1 of LHC proton–proton collision data collected with the CMS detector at $$\sqrt{s}=13\,\text {TeV} $$ ...s=13TeV . The measurement uses the $${\mathrm {t}\overline{\mathrm {t}}}$$ tt¯ all-jets final state. A kinematic fit is performed to reconstruct the decay of the $${\mathrm {t}\overline{\mathrm {t}}}$$ tt¯ system and suppress the multijet background. Using the ideogram method, the top quark mass ($$m_{\mathrm {t}}$$ mt ) is determined, simultaneously constraining an additional jet energy scale factor ($$\text {JSF}$$ JSF ). The resulting value of $$m_{\mathrm {t}} =172.34\pm 0.20\,\text {(stat+JSF)} \pm 0.70\,\text {(syst)} \,\text {GeV} $$ mt=172.34±0.20(stat+JSF)±0.70(syst)GeV is in good agreement with previous measurements. In addition, a combined measurement that uses the $${\mathrm {t}\overline{\mathrm {t}}}$$ tt¯ lepton+jets and all-jets final states is presented, using the same mass extraction method, and provides an $$m_{\mathrm {t}}$$ mt measurement of $$172.26\pm 0.07\,\text {(stat+JSF)} \pm 0.61\,\text {(syst)} \,\text {GeV} $$ 172.26±0.07(stat+JSF)±0.61(syst)GeV . This is the first combined $$m_{\mathrm {t}}$$ mt extraction from the lepton+jets and all-jets channels through a single likelihood function.
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