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Constraints on the χc1 versus χc2 Polarizations in Proton-Proton Collisions at √s=8 TeV
(2020)Physical Review LettersThe polarizations of promptly produced χc1 and χc2 mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at √s=8 TeV. The χc states are reconstructed via their radiative decays χc→J/ψγ, with the photons being measured through conversions to e+e−, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χc2 to χc1 yield ...Journal Article -
Measurements of angular distance and momentum ratio distributions in three-jet and Z + two-jet final states in pp collisions
(2021)The European Physical Journal CCollinear (small-angle) and large-angle, as well as soft and hard radiations are investigated in three-jet and Z + two-jet events collected in proton-proton collisions at the LHC. The normalized production cross sections are measured as a function of the ratio of transverse momenta of two jets and their angular separation. The measurements in the three-jet and Z + two-jet events are based on data collected at a center-of-mass energy of ...Journal Article -
Measurement of differential cross sections and charge ratios for t-channel single top quark production in proton–proton collisions at √s=13Te
(2020)The European Physical Journal CA measurement is presented of differential cross sections for t-channel single top quark and antiquark production in proton–proton collisions at a centre-of-mass energy of 13TeV by the CMS experiment at the LHC. From a data set corresponding to an integrated luminosity of 35.9fb−1, events containing one muon or electron and two or three jets are analysed. The cross section is measured as a function of the top quark transverse momentum ...Journal Article -
Search for top squark production in fully hadronic final states in proton-proton collisions at s =13 TeV
(2021)Physical Review DA search for production of the supersymmetric partners of the top quark, top squarks, is presented. The search is based on proton-proton collision events containing multiple jets, no leptons, and large transverse momentum imbalance. The data were collected with the CMS detector at the CERN LHC at a center-of-mass energy of 13 TeV, and correspond to an integrated luminosity of 137 fb−1. The targeted signal production scenarios are direct ...Journal Article -
Measurement of prompt D0 and D‾0 meson azimuthal anisotropy and search for strong electric fields in PbPb collisions at sNN=5.02TeV
(2021)Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy PhysicsThe strong Coulomb field created in ultrarelativistic heavy ion collisions is expected to produce a rapidity-dependent difference (Δv2) in the second Fourier coefficient of the azimuthal distribution (elliptic flow, v2) between D0 (u‾c) and D‾0 (uc‾) mesons. Motivated by the search for evidence of this field, the CMS detector at the LHC is used to perform the first measurement of Δv2. The rapidity-averaged value is found to be ...Journal Article -
Search for disappearing tracks in proton-proton collisions at s=13TeV
(2020)Physics Letters BA search is presented for long-lived charged particles that decay within the volume of the silicon tracker of the CMS experiment. Such particles can produce events with an isolated track that is missing hits in the outermost layers of the silicon tracker, and is also associated with little energy deposited in the calorimeters and no hits in the muon detectors. The search for events with this “disappearing track” signature is performed in ...Journal Article -
Search for physics beyond the standard model in events with jets and two same-sign or at least three charged leptons in proton-proton collisions at √s=13TeV
(2020)The European Physical Journal CA 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 137fb−1 at a center-of-mass energy of 13TeV, 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 ...Journal Article -
Evidence for Top Quark Production in Nucleus-Nucleus Collisions
(2020)Physical Review LettersUltrarelativistic heavy ion collisions recreate in the laboratory the thermodynamical conditions prevailing in the early universe up to 10−6 sec, thereby allowing the study of the quark-gluon plasma (QGP), a state of quantum chromodynamics (QCD) matter with deconfined partons. The top quark, the heaviest elementary particle known, is accessible in nucleus-nucleus collisions at the CERN LHC, and constitutes a novel probe of the QGP. Here, ...Journal Article -
Production of Λc+ baryons in proton-proton and lead-lead collisions at sNN=5.02TeV
(2020)Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy PhysicsThe transverse momentum (pT) spectra of inclusively produced Λc + baryons are measured via the exclusive decay channel Λc +→pK−π+ using the CMS detector at the LHC. Spectra are measured as a function of transverse momentum in proton-proton (pp) and lead-lead (PbPb) collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The measurement is performed within the Λc + rapidity interval |y|<1 in the pT range of 5–20GeV/c in pp and ...Journal Article -
Measurement of the tt‾bb‾ production cross section in the all-jet final state in pp collisions at s=13 TeV
(2020)Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy PhysicsA measurement of the production cross section of top quark pairs in association with two b jets (tt‾bb‾) is presented using data collected in proton-proton collisions at s=13 TeV by the CMS detector at the LHC corresponding to an integrated luminosity of 35.9 fb−1. The cross section is measured in the all-jet decay channel of the top quark pair by selecting events containing at least eight jets, of which at least two are identified as ...Journal Article