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The strange quark content of the proton is probed through the measurement of the production cross section for a W boson and a charm (c) quark in proton-proton collisions at a center-of-mass energy of 13 [Formula omitted]. The analysis uses a data sample corresponding to a total integrated luminosity of 138 [Formula omitted] collected with 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 jets are tagged using the presence of a muon or a secondary vertex inside the jet. The [Formula omitted] production cross section and the cross section ratio [Formula omitted] are measured inclusively and differentially as functions of the transverse momentum and the pseudorapidity of the lepton originating from the W boson decay. The precision of the measurements is improved with respect to previous studies, reaching 1% in [Formula omitted]. The measurements are compared with theoretical predictions up to next-to-next-to-leading order in perturbative quantum chromodynamics.

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 [Formula omitted] by the CMS experiment at the LHC, corresponding to an integrated luminosity of 138 [Formula omitted]. The 95% confidence level upper limit set on the branching fraction of the 125 [Formula omitted] Higgs boson to invisible particles, [Formula omitted], is 0.54 (0.39 expected), assuming standard model production cross sections. The results of this analysis are combined with previous [Formula omitted] searches carried out at [Formula omitted], 8, and 13 [Formula omitted] in complementary production modes. The combined upper limit at 95% confidence level on [Formula omitted] is 0.15 (0.08 expected).

The mass of the top quark is measured in 36.3 [Formula omitted] of LHC proton-proton collision data collected with the CMS detector at [Formula omitted]. 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 [Formula omitted]. This approach significantly improves the precision over previous measurements.

Multijet events at large transverse momentum ( [Formula omitted]) are measured at [Formula omitted] using data recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of [Formula omitted]. The multiplicity of jets with [Formula omitted] that are produced in association with a high- [Formula omitted] dijet system is measured in various ranges of the [Formula omitted] of the jet with the highest transverse momentum and as a function of the azimuthal angle difference [Formula omitted] between the two highest [Formula omitted] jets in the dijet system. The differential production cross sections are measured as a function of the transverse momenta of the four highest [Formula omitted] 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.

The production of Z bosons associated with jets is measured in [Formula omitted] collisions at [Formula omitted] with data recorded with the CMS experiment at the LHC corresponding to an integrated luminosity of 36.3 [Formula omitted]. The multiplicity of jets with transverse momentum [Formula omitted] is measured for different regions of the Z boson's [Formula omitted], from lower than 10 [Formula omitted] to higher than 100 [Formula omitted]. The azimuthal correlation [Formula omitted] between the Z boson and the leading jet, as well as the correlations between the two leading jets are measured in three regions of [Formula omitted]. 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 [Formula omitted] regions.

The double differential cross sections of the Drell-Yan lepton pair ( [Formula omitted], dielectron or dimuon) production are measured as functions of the invariant mass [Formula omitted], transverse momentum [Formula omitted], and [Formula omitted]. The [Formula omitted] observable, derived from angular measurements of the leptons and highly correlated with [Formula omitted], is used to probe the low- [Formula omitted] region in a complementary way. Dilepton masses up to 1 [Formula omitted] 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 [Formula omitted] ranges to those in the Z mass peak interval are presented. The collected data correspond to an integrated luminosity of 36.3 [Formula omitted] of proton-proton collisions recorded with the CMS detector at the LHC at a centre-of-mass energy of 13 [Formula omitted]. 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 [Formula omitted] leptons, are presented, using a sample of proton-proton collisions collected with the CMS experiment at a center-of-mass energy of [Formula omitted], corresponding to an integrated luminosity of 138 [Formula omitted]. 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 [Formula omitted] 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 [Formula omitted] for inclusive Higgs boson production, [Formula omitted] ( [Formula omitted]) for the production mainly via gluon fusion (vector boson fusion), and [Formula omitted] for vector boson associated Higgs boson production.

A search is reported for pairs of light Higgs bosons ( [Formula omitted]) produced in supersymmetric cascade decays in final states with small missing transverse momentum. A data set of LHC [Formula omitted] collisions collected with the CMS detector at [Formula omitted] and corresponding to an integrated luminosity of 138 [Formula omitted] is used. The search targets events where both [Formula omitted] bosons decay into [Formula omitted] 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 [Formula omitted] 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 [Formula omitted] branching fraction of the [Formula omitted] in a benchmark model containing almost mass-degenerate gluinos and light-flavour squarks. Under the assumption of an SM-like [Formula omitted] branching fraction, [Formula omitted] bosons with masses in the range 40-120 [Formula omitted] arising from the decays of squarks or gluinos with a mass of 1200-2500 [Formula omitted] are excluded at 95% confidence level.

Production cross sections of the standard model Higgs boson decaying to a pair of W bosons are measured in proton-proton collisions at a center-of-mass energy of 13 [Formula omitted]. The analysis targets Higgs bosons produced via gluon fusion, vector boson fusion, and in association with a W or Z boson. Candidate events are required to have at least two charged leptons and moderate missing transverse momentum, targeting events with at least one leptonically decaying W boson originating from the Higgs boson. Results are presented in the form of inclusive and differential cross sections in the simplified template cross section framework, as well as couplings of the Higgs boson to vector bosons and fermions. The data set collected by the CMS detector during 2016-2018 is used, corresponding to an integrated luminosity of 138 [Formula omitted]. The signal strength modifier [Formula omitted], defined as the ratio of the observed production rate in a given decay channel to the standard model expectation, is measured to be [Formula omitted]. All results are found to be compatible with the standard model within the uncertainties.

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