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Charged-particle nuclear modification factors in PbPb and pPb collisions at √sNN=5.02 TeV
(2017)Journal of High Energy PhysicsThe spectra of charged particles produced within the pseudorapidity window |η| < 1 at sNN−−−−√=5.02 TeV are measured using 404 μb−1 of PbPb and 27.4 pb−1 of pp data collected by the CMS detector at the LHC in 2015. The spectra are presented over the transverse momentum ranges spanning 0.5 < p T < 400 GeV in pp and 0.7 < p T < 400 GeV in PbPb collisions. The corresponding nuclear modification factor, R AA, is measured in bins of collision ...Journal Article -
Measurement of prompt J/ψ pair production in pp collisions at √s = 7 Tev
(2014)Journal of High Energy PhysicsProduction of prompt J/ψ meson pairs in proton-proton collisions at s√ = 7 TeV is measured with the CMS experiment at the LHC in a data sample corresponding to an integrated luminosity of about 4.7 fb−1. The two J/ψ mesons are fully reconstructed via their decays into μ + μ − pairs. This observation provides for the first time access to the high-transverse-momentum region of J/ψ pair production where model predictions are not yet established. ...Journal Article -
Search for standard model production of four top quarks in the lepton + jets channel in pp collisions at √s = 8 TeV
(2014)Journal of High Energy PhysicsA search is presented for standard model (SM) production of four top quarks (tt¯tt¯) in pp collisions in the lepton + jets channel. The data correspond to an integrated luminosity of 19.6 fb−1 recorded at a centre-of-mass energy of 8 TeV with the CMS detector at the CERN LHC. The expected cross section for SM tt¯tt¯ production is σSMtt¯tt¯≈1fb. A combination of kinematic reconstruction and multivariate techniques is used to distinguish ...Journal Article -
Observation of top quark pairs produced in association with a vector boson in pp collisions at √s=8 TeV
(2016)Journal of High Energy PhysicsMeasurements of the cross sections for top quark pairs produced in association with a W or Z boson are presented, using 8 TeV pp collision data corresponding to an integrated luminosity of 19.5 fb−1, collected by the CMS experiment at the LHC. Final states are selected in which the associated W boson decays to a charged lepton and a neutrino or the Z boson decays to two charged leptons. Signal events are identified by matching reconstructed ...Journal Article -
Search for the associated production of a Higgs boson with a single top quark in proton-proton collisions at √s= 8 TeV
(2016)Journal of High Energy PhysicsThis paper presents the search for the production of a Higgs boson in association with a single top quark (tHq), using data collected in proton-proton collisions at a center-of-mass energy of 8 TeV corresponding to an integrated luminosity of 19.7 fb−1. The search exploits a variety of Higgs boson decay modes resulting in final states with photons, bottom quarks, and multiple charged leptons, including tau leptons, and employs a variety ...Journal Article -
Measurement of diffractive dissociation cross sections in pp collisions at √s = 7 TeV
(2015)Physical Review DMeasurements of diffractive dissociation cross sections in pp collisions at √s=7 TeV are presented in kinematic regions defined by the masses MX and MY of the two final-state hadronic systems separated by the largest rapidity gap in the event. Differential cross sections are measured as a function of ξX=M2X/s in the region −5.5<log10ξX<−2.5, for log10MY<0.5, dominated by single dissociation (SD), and 0.5<log10MY<1.1, dominated by double ...Journal Article -
Searches for new physics using the tt ¯ invariant mass distribution in pp collisions at s √ =8 TeV
(2013)Physical Review LettersSearches for anomalous top quark-antiquark production are presented, based on pp collisions at √s=8 TeV. The data, corresponding to an integrated luminosity of 19.7 fb−1, were collected with the CMS detector at the LHC. The observed t¯t invariant mass spectrum is found to be compatible with the standard model prediction. Limits on the production cross section times branching fraction probe, for the first time, a region of parameter space ...Journal Article -
Measurement of the differential cross sections for top quark pair production as a function of kinematic event variables in pp collisions at √s=7 and 8 TeV
(2016)Physical Review DMeasurements are reported of the normalized differential cross sections for top quark pair production with respect to four kinematic event variables: the missing transverse energy; the scalar sum of the jet transverse momentum (pT); the scalar sum of the pT of all objects in the event; and the pT of leptonically decaying W bosons from top quark decays. The data sample, collected using the CMS detector at the LHC, consists of 5.0 fb−1 of ...Journal Article -
Search for the standard model Higgs boson produced in association with a W or a Z boson and decaying to bottom quarks
(2014)Physical Review DA search for the standard model Higgs boson (H) decaying to b¯b when produced in association with a weak vector boson (V) is reported for the following channels: W(μν)H, W(eν)H, W(τν)H, Z(μμ)H, Z(ee)H, and Z(νν)H. The search is performed in data samples corresponding to integrated luminosities of up to 5.1 inverse femtobarns at √s=7 TeV and up to 18.9 fb−1 at √s=8 TeV, recorded by the CMS experiment at the LHC. An excess of events is ...Journal Article -
Study of Z production in PbPb and pp collisions at √sNN = 2.76 TeV in the dimuon and dielectron decay channels
(2015)Journal of High Energy PhysicsThe production of Z bosons is studied in the dimuon and dielectron decay channels in PbPb and pp collisions at sNN−−−−√=2.76 TeV, using data collected by the CMS experiment at the LHC. The PbPb data sample corresponds to an integrated luminosity of about 166 μb−1, while the pp data sample collected in 2013 at the same nucleon-nucleon centre-of-mass energy has an integrated luminosity of 5.4 pb−1. The Z boson yield is measured as a function ...Journal Article