Search
Results
-
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 -
Measurement of B-c(2S)(+) and B-c*(2S)(+) cross section ratios in proton-proton collisions at root s=13 TeV
(2020)Physical ReviewThe ratios of the B-c (2S)(+) to B-c(+), B-c(*)(2S)(+) to B-c(+), and Bc(2S)(+) to Bco2STHORNthorn production cross sections are measured in proton-proton collisions at root s = 13 TeV, using a data sample collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 143 fb(-1). The three measurements are made in the Bthornc meson phase space region defined by the transverse momentum p(T) > 15 GeV and absolute ...Journal Article -
Measurement of the top quark Yukawa coupling from t t ¯ kinematic distributions in the dilepton final state in proton-proton collisions at s =13 TeV
(2020)Physical Review DA measurement of the Higgs boson Yukawa coupling to the top quark is presented using proton-proton collision data at √s=13 TeV, corresponding to an integrated luminosity of 137 fb−1, recorded with the CMS detector. The coupling strength with respect to the standard model value, Yt, is determined from kinematic distributions in t¯t final states containing ee, μμ, or eμ pairs. Variations of the Yukawa coupling strength lead to modified ...Journal Article -
Measurements of production cross sections of WZ and same-sign WW boson pairs in association with two jets in proton-proton collisions at s=13TeV
(2020)Physics Letters BMeasurements of production cross sections of WZ and same-sign WW boson pairs in association with two jets in proton-proton collisions at s=13TeV at the LHC are reported. The data sample corresponds to an integrated luminosity of 137fb−1, collected with the CMS detector during 2016–2018. The measurements are performed in the leptonic decay modes [Formula presented] and [Formula presented], where ℓ,ℓ′=e, [Formula presented]. Differential ...Journal Article -
Observation of the B0s→X(3872)ϕ Decay
(2020)Physical Review LettersUsing a data sample of proton-proton collisions at √s=13 TeV, corresponding to an integrated luminosity of 140 fb−1 collected by the CMS experiment in 2016–2018, the B0s→X(3872)ϕ decay is observed. Decays into J/ψπ+π− and K+K− are used to reconstruct, respectively, the X(3872) and ϕ. The ratio of the product of branching fractions B[B0s→X(3872)ϕ]B[X(3872)→J/ψπ+π−] to the product B[B0s→ψ(2S)ϕ]B[ψ(2S)→J/ψπ+π−] is measured to be ...Journal Article -
Performance of the CMS Level-1 trigger in proton-proton collisions at √s = 13 TeV
(2020)Journal of InstrumentationAt the start of Run 2 in 2015, the LHC delivered proton-proton collisions at a center-of-mass energy of 13\TeV. During Run 2 (years 2015–2018) the LHC eventually reached a luminosity of 2.1× 1034 cm-2s-1, almost three times that reached during Run 1 (2009–2013) and a factor of two larger than the LHC design value, leading to events with up to a mean of about 50 simultaneous inelastic proton-proton collisions per bunch crossing (pileup). ...Journal Article -
Studies of Charm Quark Diffusion inside Jets Using Pb-Pb and pp Collisions at root s(NN)=5.02 TeV
(2020)Physical Review LettersThe first study of charm quark diffusion with respect to the jet axis in heavy ion collisions is presented. The measurement is performed using jets with pjetT>60 GeV/c and D0 mesons with pDT>4 GeV/c in lead-lead (Pb-Pb) and proton-proton (pp) collisions at a nucleon-nucleon center-of-mass energy of √sNN=5.02 TeV, recorded by the CMS detector at the LHC. The radial distribution of D0 mesons with respect to the jet axis is sensitive to ...Journal Article -
Measurement of CKM matrix elements in single top quark t-channel production in proton-proton collisions at s=13 TeV
(2020)Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy PhysicsThe first direct, model-independent measurement is presented of the modulus of the Cabibbo–Kobayashi–Maskawa (CKM) matrix elements |η|Vtb, |η|Vtd, and |η|Vts, in final states enriched in single top quark t-channel events. The analysis uses proton-proton collision data from the LHC, collected during 2016 by the CMS experiment, at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb−1. Processes directly ...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 -
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