The mass of the top quark is measured in 36.3
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Abstract of LHC proton–proton collision data collected with the CMS detector at$$\,\text {fb}^{-1}$$ . The measurement uses a sample of top quark pair candidate events containing one isolated electron or muon and at least four jets in the final state. For each event, the mass is reconstructed from a kinematic fit of the decay products to a top quark pair hypothesis. A profile likelihood method is applied using up to four observables per event to extract the top quark mass. The top quark mass is measured to be$$\sqrt{s}=13\,\text {Te}\hspace{-.08em}\text {V} $$ . This approach significantly improves the precision over previous measurements.$$171.77\pm 0.37\,\text {Ge}\hspace{-.08em}\text {V} $$ -
Abstract A generic search is presented for the associated production of a Z boson or a photon with an additional unspecified massive particle X,
, in proton-tagged events from proton–proton collisions at$${\textrm{pp}}\rightarrow {\textrm{pp}} +{{\textrm{Z}}}/\upgamma +{{\textrm{X}}} $$ , recorded in 2017 with the CMS detector and the CMS-TOTEM precision proton spectrometer. The missing mass spectrum is analysed in the 600–1600 GeV range and a fit is performed to search for possible deviations from the background expectation. No significant excess in data with respect to the background predictions has been observed. Model-independent upper limits on the visible production cross section of$$\sqrt{s}=13\, \textrm{TeV}$$ are set.$${\textrm{pp}}\rightarrow {\textrm{pp}} +{{\textrm{Z}}}/\upgamma +{{\textrm{X}}} $$ -
Abstract The production of Z bosons associated with jets is measured in $$\text {p}\text {p}$$ pp collisions at $$\sqrt{s}=13\,\text {Te}\hspace{-.08em}\text {V} $$ s = 13 Te V with data recorded with the CMS experiment at the LHC corresponding to an integrated luminosity of 36.3 $$\,\text {fb}^{-1}$$ fb - 1 . The multiplicity of jets with transverse momentum $$p_{\textrm{T}} > 30\,\text {Ge}\hspace{-.08em}\text {V} $$ p T > 30 Ge V is measured for different regions of the Z boson’s $$p_{\textrm{T}} (\text {Z })$$ p T ( Z ) , from lower than 10 $$\,\text {Ge}\hspace{-.08em}\text {V}$$ Ge V to higher than 100 $$\,\text {Ge}\hspace{-.08em}\text {V}$$ Ge V . The azimuthal correlation $$\varDelta \phi $$ Δ ϕ between the Z boson and the leading jet, as well as the correlations between the two leading jets are measured in three regions of $$p_{\textrm{T}} (\text {Z })$$ p T ( Z ) . The measurements are compared with several predictions at leading and next-to-leading orders, interfaced with parton showers. Predictions based on transverse-momentum dependent parton distributions and corresponding parton showers give a good description of the measurement in the regions where multiple parton interactions and higher jet multiplicities are not important. The effects of multiple parton interactions are shown to be important to correctly describe the measured spectra in the low $$p_{\textrm{T}} (\text {Z })$$ p T ( Z ) regions.more » « less
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Abstract Multijet events at large transverse momentum ( $$p_{\textrm{T}}$$ p T ) are measured at $$\sqrt{s}=13\,\text {TeV} $$ s = 13 TeV using data recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of $$36.3{\,\text {fb}^{-1}} $$ 36.3 fb - 1 . The multiplicity of jets with $$p_{\textrm{T}} >50\,\text {GeV} $$ p T > 50 GeV that are produced in association with a high- $$p_{\textrm{T}}$$ p T dijet system is measured in various ranges of the $$p_{\textrm{T}}$$ p T of the jet with the highest transverse momentum and as a function of the azimuthal angle difference $$\varDelta \phi _{1,2}$$ Δ ϕ 1 , 2 between the two highest $$p_{\textrm{T}}$$ p T jets in the dijet system. The differential production cross sections are measured as a function of the transverse momenta of the four highest $$p_{\textrm{T}}$$ p T jets. The measurements are compared with leading and next-to-leading order matrix element calculations supplemented with simulations of parton shower, hadronization, and multiparton interactions. In addition, the measurements are compared with next-to-leading order matrix element calculations combined with transverse-momentum dependent parton densities and transverse-momentum dependent parton shower.more » « less
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Abstract A search is reported for pairs of light Higgs bosons (
) produced in supersymmetric cascade decays in final states with small missing transverse momentum. A data set of LHC$${\textrm{H}} _1$$ collisions collected with the CMS detector at$$\hbox {pp}$$ and corresponding to an integrated luminosity of 138$$\sqrt{s}=13\,\text {TeV} $$ is used. The search targets events where both$$\,\text {fb}^{-1}$$ bosons decay into Equation missing<#comment/>pairs that are reconstructed as large-radius jets using substructure techniques. No evidence is found for an excess of events beyond the background expectations of the standard model (SM). Results from the search are interpreted in the next-to-minimal supersymmetric extension of the SM, where a “singlino” of small mass leads to squark and gluino cascade decays that can predominantly end in a highly Lorentz-boosted singlet-like$${\textrm{H}} _1$$ and a singlino-like neutralino of small transverse momentum. Upper limits are set on the product of the squark or gluino pair production cross section and the square of the Equation missing<#comment/>branching fraction of the$${\textrm{H}} _1$$ in a benchmark model containing almost mass-degenerate gluinos and light-flavour squarks. Under the assumption of an SM-like Equation missing<#comment/>branching fraction,$${\textrm{H}} _1$$ bosons with masses in the range 40–120$${\textrm{H}} _1$$ arising from the decays of squarks or gluinos with a mass of 1200–2500$$\,\text {GeV}$$ are excluded at 95% confidence level.$$\,\text {GeV}$$ -
Abstract Measurements of Higgs boson production, where the Higgs boson decays into a pair of
leptons, are presented, using a sample of proton-proton collisions collected with the CMS experiment at a center-of-mass energy of Equation missing<#comment/>, corresponding to an integrated luminosity of 138$$\uptau $$ . Three analyses are presented. Two are targeting Higgs boson production via gluon fusion and vector boson fusion: a neural network based analysis and an analysis based on an event categorization optimized on the ratio of signal over background events. These are complemented by an analysis targeting vector boson associated Higgs boson production. Results are presented in the form of signal strengths relative to the standard model predictions and products of cross sections and branching fraction to$$\,\text {fb}^{-1}$$ leptons, in up to 16 different kinematic regions. For the simultaneous measurements of the neural network based analysis and the analysis targeting vector boson associated Higgs boson production signal strengths are found to be$$\uptau $$ for inclusive Higgs boson production,$$0.82\pm 0.11$$ ($$0.67\pm 0.19$$ ) for the production mainly via gluon fusion (vector boson fusion), and$$0.81\pm 0.17$$ for vector boson associated Higgs boson production.$$1.79\pm 0.45$$ -
Abstract The double differential cross sections of the Drell–Yan lepton pair (
, dielectron or dimuon) production are measured as functions of the invariant mass$$\ell ^+\ell ^-$$ , transverse momentum$$m_{\ell \ell }$$ , and$$p_{\textrm{T}} (\ell \ell )$$ . The$$\varphi ^{*}_{\eta }$$ observable, derived from angular measurements of the leptons and highly correlated with$$\varphi ^{*}_{\eta }$$ , is used to probe the low-$$p_{\textrm{T}} (\ell \ell )$$ region in a complementary way. Dilepton masses up to 1$$p_{\textrm{T}} (\ell \ell )$$ are 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$$\,\text {Te\hspace{-.08em}V}$$ ranges to those in the Z mass peak interval are presented. The collected data correspond to an integrated luminosity of 36.3$$m_{\ell \ell }$$ of proton–proton collisions recorded with the CMS detector at the LHC at a centre-of-mass energy of 13$$\,\text {fb}^{-1}$$ . Measurements are compared with predictions based on perturbative quantum chromodynamics, including soft-gluon resummation.$$\,\text {Te\hspace{-.08em}V}$$ -
Abstract A measurement of the jet mass distribution in hadronic decays of Lorentz-boosted top quarks is presented. The measurement is performed in the lepton + jets channel of top quark pair production ( $$\hbox {t}\overline{\hbox {t}}$$ t t ¯ ) events, where the lepton is an electron or muon. The products of the hadronic top quark decay are reconstructed using a single large-radius jet with transverse momentum greater than 400 $$\,\text {Ge}\hspace{-.08em}\text {V}$$ Ge V . The data were collected with the CMS detector at the LHC in proton-proton collisions and correspond to an integrated luminosity of 138 $$\,\text {fb}^{-1}$$ fb - 1 . The differential $$\hbox {t}\overline{\hbox {t}}$$ t t ¯ production cross section as a function of the jet mass is unfolded to the particle level and is used to extract the top quark mass. The jet mass scale is calibrated using the hadronic W boson decay within the large-radius jet. The uncertainties in the modelling of the final state radiation are reduced by studying angular correlations in the jet substructure. These developments lead to a significant increase in precision, and a top quark mass of $$173.06 \pm 0.84\,\text {Ge}\hspace{-.08em}\text {V} $$ 173.06 ± 0.84 Ge V .more » « less