The measurement of the luminosity recorded by the CMS detector installed at LHC interaction point 5, using proton-proton collisions at Formula omitted in 2015 and 2016, is reported. The absolute ...luminosity scale is measured for individual bunch crossings using beam-separation scans (the van der Meer method), with a relative precision of 1.3 and 1.0% in 2015 and 2016, respectively. The dominant sources of uncertainty are related to residual differences between the measured beam positions and the ones provided by the operational settings of the LHC magnets, the factorizability of the proton bunch spatial density functions in the coordinates transverse to the beam direction, and the modeling of the effect of electromagnetic interactions among protons in the colliding bunches. When applying the van der Meer calibration to the entire run periods, the integrated luminosities when CMS was fully operational are 2.27 and 36.3 Formula omitted in 2015 and 2016, with a relative precision of 1.6 and 1.2%, respectively. These are among the most precise luminosity measurements at bunched-beam hadron colliders.
A search for charged Higgs bosons produced in vector boson fusion processes and decaying into vector bosons, using proton-proton collisions at Formula omitted at the LHC, is reported. The data sample ...corresponds to an integrated luminosity of 137 Formula omitted collected with the CMS detector. Events are selected by requiring two or three electrons or muons, moderate missing transverse momentum, and two jets with a large rapidity separation and a large dijet mass. No excess of events with respect to the standard model background predictions is observed. Model independent upper limits at 95% confidence level are reported on the product of the cross section and branching fraction for vector boson fusion production of charged Higgs bosons as a function of mass, from 200 to 3000 Formula omitted. The results are interpreted in the context of the Georgi-Machacek model.
Results of the Model Unspecific Search in CMS (MUSiC), using proton-proton collision data recorded at the LHC at a centre-of-mass energy of 13 Formula omitted, corresponding to an integrated ...luminosity of 35.9 Formula omitted, are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.
Production cross sections of the Higgs boson are measured in the Formula omitted ( Formula omitted) decay channel. A data sample of proton-proton collisions at a center-of-mass energy of 13 Formula ...omitted, collected by the CMS detector at the LHC and corresponding to an integrated luminosity of 137 Formula omitted is used. The signal strength modifier Formula omitted, defined as the ratio of the Higgs boson production rate in the Formula omitted channel to the standard model (SM) expectation, is measured to be Formula omitted at a fixed value of Formula omitted. The signal strength modifiers for the individual Higgs boson production modes are also reported. The inclusive fiducial cross section for the Formula omitted process is measured to be Formula omitted, which is compatible with the SM prediction of Formula omitted for the same fiducial region. Differential cross sections as a function of the transverse momentum and rapidity of the Higgs boson, the number of associated jets, and the transverse momentum of the leading associated jet are measured. A new set of cross section measurements in mutually exclusive categories targeted to identify production mechanisms and kinematical features of the events is presented. The results are in agreement with the SM predictions.
The production of Z boson pairs in proton-proton ( Formula omitted) collisions, Formula omitted, where Formula omitted or Formula omitted, is studied at a center-of-mass energy of 13 Formula omitted ...with the CMS detector at the CERN LHC. The data sample corresponds to an integrated luminosity of 137 Formula omitted, collected during 2016-2018. The Formula omitted production cross section, Formula omitted, measured for events with two pairs of opposite-sign, same-flavor leptons produced in the mass region Formula omitted is consistent with standard model predictions. Differential cross sections are also measured and agree with theoretical predictions. The invariant mass distribution of the four-lepton system is used to set limits on anomalous Formula omitted and Formula omitted couplings.
A search is presented for supersymmetric partners of the top quark (top squarks) in final states with two oppositely charged leptons (electrons or muons), jets identified as originating from Formula ...omittedquarks, and missing transverse momentum. The search uses data from proton-proton collisions at Formula omitted collected with the CMS detector, corresponding to an integrated luminosity of 137 Formula omitted. Hypothetical signal events are efficiently separated from the dominant top quark pair production background with requirements on the significance of the missing transverse momentum and on transverse mass variables. No significant deviation is observed from the expected background. Exclusion limits are set in the context of simplified supersymmetric models with pair-produced lightest top squarks. For top squarks decaying exclusively to a top quark and a lightest neutralino, lower limits are placed at Formula omitted confidence level on the masses of the top squark and the neutralino up to 925 and 450 Formula omitted, respectively. If the decay proceeds via an intermediate chargino, the corresponding lower limits on the mass of the lightest top squark are set up to 850 Formula omitted for neutralino masses below 420 Formula omitted. For top squarks undergoing a cascade decay through charginos and sleptons, the mass limits reach up to 1.4 Formula omitted and 900 Formula omitted respectively for the top squark and the lightest neutralino.
A data sample of events from proton-proton collisions with at least two jets, and two isolated same-sign or three or more charged leptons, is studied in a search for signatures of new physics ...phenomena. The data correspond to an integrated luminosity of Formula omitted at a center-of-mass energy of Formula omitted, collected in 2016-2018 by the CMS experiment at the LHC. The search is performed using a total of 168 signal regions defined using several kinematic variables. The properties of the events are found to be consistent with the expectations from standard model processes. Exclusion limits at 95% confidence level are set on cross sections for the pair production of gluinos or squarks for various decay scenarios in the context of supersymmetric models conserving or violating R parity. The observed lower mass limits are as large as Formula omitted for gluinos and Formula omitted for top and bottom squarks. To facilitate reinterpretations, model-independent limits are provided in a set of simplified signal regions.
Measurements are presented of the single-diffractive dijet cross section and the diffractive cross section as a function of the proton fractional momentum loss Formula omitted and the four-momentum ...transfer squared t. Both processes Formula omitted and Formula omitted, i.e. with the proton scattering to either side of the interaction point, are measured, where Formula omitted includes at least two jets; the results of the two processes are averaged. The analyses are based on data collected simultaneously with the CMS and TOTEM detectors at the LHC in proton-proton collisions at Formula omitted during a dedicated run with Formula omitted at low instantaneous luminosity and correspond to an integrated luminosity of Formula omitted. The single-diffractive dijet cross section Formula omitted, in the kinematic region Formula omitted, Formula omitted, with at least two jets with transverse momentum Formula omitted, and pseudorapidity Formula omitted, is Formula omitted. The ratio of the single-diffractive to inclusive dijet yields, normalised per unit of Formula omitted, is presented as a function of x, the longitudinal momentum fraction of the proton carried by the struck parton. The ratio in the kinematic region defined above, for x values in the range Formula omitted, is Formula omitted, where Formula omitted and Formula omitted are the single-diffractive and inclusive dijet cross sections, respectively. The results are compared with predictions from models of diffractive and nondiffractive interactions. Monte Carlo predictions based on the HERA diffractive parton distribution functions agree well with the data when corrected for the effect of soft rescattering between the spectator partons.
Anisotropies in the initial energy density distribution of the quark-gluon plasma created in high energy heavy ion collisions lead to anisotropies in the azimuthal distributions of the final-state ...particles known as collective anisotropic flow. Fourier harmonic decomposition is used to quantify these anisotropies. The higher-order harmonics can be induced by the same order anisotropies (linear response) or by the combined influence of several lower order anisotropies (nonlinear response) in the initial state. The mixed higher-order anisotropic flow and nonlinear response coefficients of charged particles are measured as functions of transverse momentum and centrality in Formula omitted collisions at nucleon-nucleon center-of-mass energies Formula omitted and 5.02 Formula omitted with the CMS detector. The results are compared with viscous hydrodynamic calculations using several different initial conditions, as well as microscopic transport model calculations. None of the models provides a simultaneous description of the mixed higher-order flow harmonics and nonlinear response coefficients.
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