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Identification of heavy, energetic, hadronically decaying particles using machine-learning techniques
(2020)Journal of InstrumentationMachine-learning (ML) techniques are explored to identify and classify hadronic decays of highly Lorentz-boosted W/Z/Higgs bosons and top quarks. Techniques without ML have also been evaluated and are included for comparison. The identification performances of a variety of algorithms are characterized in simulated events and directly compared with data. The algorithms are validated using proton-proton collision data at root S = 13 TeV, ...Journal Article -
Calibration of the CMS hadron calorimeters using proton-proton collision data at √s = 13 TeV
(2020)Journal of InstrumentationMethods are presented for calibrating the hadron calorimeter system of the CMS detector at the LHC. The hadron calorimeters of the CMS experiment are sampling calorimeters of brass and scintillator, and are in the form of one central detector and two endcaps. These calorimeters cover pseudorapidities |η| < 3 and are positioned inside the solenoidal magnet. An outer calorimeter, outside the magnet coil, covers |η| < 1.26, and a steel and ...Journal Article -
Measurements with silicon photomultipliers of dose-rate effects in the radiation damage of plastic scintillator tiles in the CMS hadron endcap calorimeter
(2020)Journal of InstrumentationMeasurements are presented of the reduction of signal output due to radiation damage for two types of plastic scintillator tiles used in the hadron endcap (HE) calorimeter of the CMS detector. The tiles were exposed to particles produced in proton-proton (pp) collisions at the CERN LHC with a center-of-mass energy of 13 TeV, corresponding to a delivered luminosity of 50 fb−1. The measurements are based on readout channels of the HE that ...Journal Article -
Measurements of (tt)over-barH Production and the CP Structure of the Yukawa Interaction between the Higgs Boson and Top Quark in the Diphoton Decay Channel
(2020)Physical Review LettersThe first observation of the (tt) over barH process in a single Higgs boson decay channel with the full reconstruction of the final state (H -> gamma gamma) is presented, with a significance of 6.6 standard deviations (sigma). The CP structure of Higgs boson couplings to fermions is measured, resulting in an exclusion of the pure CP-odd structure of the top Yukawa coupling at 3.2 sigma. The measurements are based on a sample of protonproton ...Journal Article -
The production of isolated photons in PbPb and pp collisions at √sNN = 5.02 TeV
(2020)Journal of High Energy PhysicsThe transverse energy (EγT) spectra of photons isolated from other particles are measured using proton-proton (pp) and lead-lead (PbPb) collisions at the LHC at sNN−−−√ = 5.02 TeV with integrated luminosities of 27.4 pb−1 and 404 μb−1 for pp and PbPb data, respectively. The results are presented for photons with 25 < EγT < 200 GeV in the pseudorapidity range |η| < 1.44, and for different centrality intervals for PbPb collisions. Photon ...Journal Article -
Measurement of the Jet Mass Distribution and Top Quark Mass in Hadronic Decays of Boosted Top Quarks in pp Collisions at root s=13 TeV
(2020)Physical Review LettersA measurement is reported of the jet mass distribution in hadronic decays of boosted top quarks produced in pp collisions at √s=13 TeV. The data were collected with the CMS detector at the LHC and correspond to an integrated luminosity of 35.9 fb−1. The measurement is performed in the lepton+jets channel of t¯t events, where the lepton is an electron or muon. The products of the hadronic top quark decay t→bW→bq¯q′ are reconstructed as ...Journal Article -
Measurement of the cross section for t t ¯ production with additional jets and b jets in pp collisions at √s = 13 TeV
(2020)Journal of High Energy PhysicsMeasurements of the cross section for the production of top quark pairs in association with a pair of jets from bottom quarks (σtt¯bb¯¯¯) and in association with a pair of jets from quarks of any flavor or gluons (σtt¯jj) and their ratio are presented. The data were collected in proton-proton collisions at a center-of-mass energy of 13 TeV by the CMS experiment at the LHC in 2016 and correspond to an integrated luminosity of 35.9 fb−1. ...Journal Article -
Combination of the W boson polarization measurements in top quark decays using ATLAS and CMS data at √s = 8 TeV
(2020)Journal of High Energy PhysicsThe combination of measurements of the W boson polarization in top quark decays performed by the ATLAS and CMS collaborations is presented. The measurements are based on proton-proton collision data produced at the LHC at a centre-of-mass energy of 8 TeV, and corresponding to an integrated luminosity of about 20 fb−1 for each experiment. The measurements used events containing one lepton and having different jet multiplicities in the final ...Journal Article -
Measurement of the integrated and differential t¯t production cross sections for high-pT top quarks in pp collisions at √s=8 TeV
(2016)Physical Review DThe cross section for pair production of top quarks (t¯t) with high transverse momenta is measured in pp collisions, collected with the CMS detector at the LHC with √s=8 TeV in data corresponding to an integrated luminosity of 19.7 fb−1. The measurement is performed using lepton+jets events, where one top quark decays semileptonically, while the second top quark decays to a hadronic final state. The hadronic decay is reconstructed as a ...Journal Article