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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 ( ) 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 . The data were collected with the CMS detector at the LHC in proton-proton collisions and correspond to an integrated luminosity of 138 . The differential 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 .

Here, a measurement of the double-differential inclusive jet cross section as a function of jet transverse momentum pT and absolute jet rapidity |y| is presented. The analysis is based on proton-proton collisions collected by the CMS experiment at the LHC at a centre-of-mass energy of 13 TeV. The data samples correspond to integrated luminosities of 71 and 44 inverse picobarns for |y| < 3 and 3.2 < |y| < 4.7, respectively. Jets are reconstructed with the anti-kt clustering algorithm for two jet sizes, R, of 0.7 and 0.4, in a phase space region covering jet pT up to 2 TeV and jet rapidity up to |y| = 4.7. Predictions of perturbative quantum chromodynamics at next-to-leading order precision, complemented with electroweak and nonperturbative corrections, are used to compute the absolute scale and the shape of the inclusive jet cross section. The cross section difference in R, when going to a smaller jet size of 0.4, is best described by Monte Carlo event generators with next-to-leading order predictions matched to parton showering, hadronisation, and multiparton interactions. In the phase space accessible with the new data, this measurement provides a first indication that jet physics is as well understood at √s = 13 TeV as at smaller centre-of-mass energies.

Stringent limits are set on the long-lived lepton-like sector of the phenomenological minimal supersymmetric standard model (pMSSM) and the anomaly-mediated supersymmetry breaking (AMSB) model. We derived the limits from the results presented in a recent search for long-lived charged particles in proton–proton collisions, based on data collected by the CMS detector at a centre-of-mass energy of 8 TeV at the Large Hadron Collider. In the pMSSM parameter sub-space considered, 95.9 % of the points predicting charginos with a lifetime of at least 10 ns are excluded. Furthermore, these constraints on the pMSSM are the first obtained at the LHC. Charginos with a lifetime greater than 100 ns and masses up to about 800 GeV in the AMSB model are also excluded. Furthermore, the method described can also be used to set constraints on other models.

The production of prompt $$ {\\Lambda}_{\\textrm{c}}^{+} $$ Λ c + baryons is measured via the exclusive decay channel $$ {\\Lambda}_{\\textrm{c}}^{+}\\to p{\\textrm{K}}^{-}{\\pi}^{+} $$ Λ c + → p K − π + at a center-of-mass energy per nucleon pair of 5.02 TeV, using proton-proton (pp) and lead-lead (PbPb) collision data collected by the CMS experiment at the CERN LHC. The pp and PbPb data were obtained in 2017 and 2018 with integrated luminosities of 252 and 0.607 nb − 1 , respectively. The measurements are performed within the $$ {\\Lambda}_{\\textrm{c}}^{+} $$ Λ c + rapidity interval | y | < 1 with transverse momentum ( p T ) ranges of 3–30 and 6–40 GeV/ c for pp and PbPb collisions, respectively. Compared to the yields in pp collisions scaled by the expected number of nucleon-nucleon interactions, the observed yields of $$ {\\Lambda}_{\\textrm{c}}^{+} $$ Λ c + with p T > 10 GeV/ c are strongly suppressed in PbPb collisions. The level of suppression depends significantly on the collision centrality. The $$ {\\Lambda}_{\\textrm{c}}^{+} $$ Λ c + / D 0 production ratio is similar in PbPb and pp collisions at p T > 10 GeV/ c , suggesting that the coalescence process does not play a dominant role in prompt $$ {\\Lambda}_{\\textrm{c}}^{+} $$ Λ c + baryon production at higher p T .

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.

A search for decays to invisible particles of Higgs bosons produced in association with a top-antitop quark pair or a vector boson, which both decay to a fully hadronic final state, has been performed using proton-proton collision data collected at $${\\sqrt{s}=13\\,\\text {Te}\\hspace{-.08em}\\text {V}}$$ s = 13 Te V by the CMS experiment at the LHC, corresponding to an integrated luminosity of 138 $$\\,\\text {fb}^{-1}$$ fb - 1 . The 95% confidence level upper limit set on the branching fraction of the 125 $$\\,\\text {Ge}\\hspace{-.08em}\\text {V}$$ Ge V Higgs boson to invisible particles, $${\\mathcal {B}({\\textrm{H}} \\rightarrow \\text {inv})}$$ B ( H → inv ) , is 0.54 (0.39 expected), assuming standard model production cross sections. The results of this analysis are combined with previous $${\\mathcal {B}({\\textrm{H}} \\rightarrow \\text {inv})}$$ B ( H → inv ) searches carried out at $${\\sqrt{s}=7}$$ s = 7 , 8, and 13 $$\\,\\text {Te}\\hspace{-.08em}\\text {V}$$ Te V in complementary production modes. The combined upper limit at 95% confidence level on $${\\mathcal {B}({\\textrm{H}} \\rightarrow \\text {inv})}$$ B ( H → inv ) is 0.15 (0.08 expected).

The double differential cross sections of the Drell–Yan lepton pair ( $$\\ell ^+\\ell ^-$$ ℓ + ℓ - , dielectron or dimuon) production are measured as functions of the invariant mass $$m_{\\ell \\ell }$$ m ℓ ℓ , transverse momentum $$p_{\\textrm{T}} (\\ell \\ell )$$ p T ( ℓ ℓ ) , and $$\\varphi ^{*}_{\\eta }$$ φ η ∗ . The $$\\varphi ^{*}_{\\eta }$$ φ η ∗ observable, derived from angular measurements of the leptons and highly correlated with $$p_{\\textrm{T}} (\\ell \\ell )$$ p T ( ℓ ℓ ) , is used to probe the low- $$p_{\\textrm{T}} (\\ell \\ell )$$ p T ( ℓ ℓ ) region in a complementary way. Dilepton masses up to 1 $$\\,\\text {Te\\hspace{-.08em}V}$$ Te V 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 $$m_{\\ell \\ell }$$ m ℓ ℓ ranges 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 - 1 of proton–proton collisions recorded with the CMS detector at the LHC at a centre-of-mass energy of 13 $$\\,\\text {Te\\hspace{-.08em}V}$$ Te V . Measurements are compared with predictions based on perturbative quantum chromodynamics, including soft-gluon resummation.

Measurements of Higgs boson production, where the Higgs boson decays into a pair of $$\\uptau $$ τ leptons, are presented, using a sample of proton-proton collisions collected with the CMS experiment at a center-of-mass energy of \"Equation missing\" , corresponding to an integrated luminosity of 138 $$\\,\\text {fb}^{-1}$$ fb - 1 . 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 $$\\uptau $$ τ 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 $$0.82\\pm 0.11$$ 0.82 ± 0.11 for inclusive Higgs boson production, $$0.67\\pm 0.19$$ 0.67 ± 0.19 ( $$0.81\\pm 0.17$$ 0.81 ± 0.17 ) for the production mainly via gluon fusion (vector boson fusion), and $$1.79\\pm 0.45$$ 1.79 ± 0.45 for vector boson associated Higgs boson production.

An analysis of dijet events in PbPb and pp collisions is performed to explore the properties of energy loss by partons traveling in a quark-gluon plasma. Data are collected at a nucleon-nucleon center-of-mass energy of 2.76 TeV at the LHC. The distribution of transverse momentum (p sub(T)) surrounding dijet systems is measured by selecting charged particles in different ranges of p sub(T) and at different angular cones of pseudorapidity and azimuth. The measurement is performed as a function of centrality of the PbPb collisions, the p sub(T) asymmetry of the jets in the dijet pair, and the distance parameter R used in the anti-k sub(T) jet clustering algorithm. In events with unbalanced dijets, PbPb collisions show an enhanced multiplicity in the hemisphere of the subleading jet, with the p sub(T) imbalance compensated by an excess of low-p sub(T) particles at large angles from the jet axes. [Figure not available: see fulltext.]

The first search for nonresonant production of Higgs boson pairs (HH) with one H decaying into four leptons and the other into a pair of b quarks is presented, using proton-proton collisions recorded at a center-of-mass energy of$$ \\sqrt{s} $$s = 13 TeV by the CMS experiment. The analyzed data correspond to an integrated luminosity of 138 fb − 1 . A 95% confidence level upper limit of 32.4 is set on the signal strength modifier μ , defined as the ratio of the observed HH production rate in the$$ \\textrm{HH}\\to {\\textrm{ZZ}}^{\\ast}\\textrm{b}\\overline{\\textrm{b}}\\to 4\\ell \\textrm{b}\\overline{\\textrm{b}} $$HH → ZZ ∗ b b ¯ → 4 ℓ b b ¯ decay channel to the standard model (SM) expectation. Possible modifications of the H trilinear coupling λ HHH with respect to the SM value are investigated. The coupling modifier κ λ , defined as λ HHH divided by its SM prediction, is constrained to be within the observed (expected) range − 8 . 8 ( − 9 . 8) < κ λ < 13 . 4 (15 . 0) at 95% confidence level.