Charged-hadron transverse-momentum and pseudorapidity distributions in proton-proton collisions at sqrt(s) = 7 TeV are measured with the inner tracking system of the CMS detector at the LHC. The charged-hadron yield is obtained by counting the number of reconstructed hits, hit-pairs, and fully reconstructed charged-particle tracks. The combination of the three methods gives a charged-particle multiplicity per unit of pseudorapidity, dN(charged)/d(eta), for |eta| < 0.5, of 5.78 +/- 0.01 (stat) +/- 0.23 (syst) for non-single-diffractive events, higher than predicted by commonly used models. The relative increase in charged-particle multiplicity from sqrt(s) = 0.9 to 7 TeV is 66.1% +/- 1.0% (stat) +/- 4.2% (syst). The mean transverse momentum is measured to be 0.545 +/- 0.005 (stat) +/- 0.015 (syst) GeV/c. The results are compared with similar measurements at lower energies.
Measured differential yield of charged hadrons as a function oftransverse momentum for pseudorapidities 0.1, 0.3, 0.5 and 0.7 for centre-of-mass energy 7000 GeV.Errors are statistical and systematic added in quadrature.
Measured differential yield of charged hadrons as a function oftransverse momentum for pseudorapidities 0.9, 1.1, 1.3 and 1.5 for centre-of-mass energy 7000 GeV.Errors are statistical and systematic added in quadrature.
Measured differential yield of charged hadrons as a function oftransverse momentum for pseudorapidities 1.7, 1.9, 2.1 and 2.3 for centre-of-mass energy 7000 GeV.Errors are statistical and systematic added in quadrature.
Measurements of inclusive charged-hadron transverse-momentum and pseudorapidity distributions are presented for proton-proton collisions at sqrt(s) = 0.9 and 2.36 TeV. The data were collected with the CMS detector during the LHC commissioning in December 2009. For non-single-diffractive interactions, the average charged-hadron transverse momentum is measured to be 0.46 +/- 0.01 (stat.) +/- 0.01 (syst.) GeV/c at 0.9 TeV and 0.50 +/- 0.01 (stat.) +/- 0.01 (syst.) GeV/c at 2.36 TeV, for pseudorapidities between -2.4 and +2.4. At these energies, the measured pseudorapidity densities in the central region, dN(charged)/d(eta) for |eta| < 0.5, are 3.48 +/- 0.02 (stat.) +/- 0.13 (syst.) and 4.47 +/- 0.04 (stat.) +/- 0.16 (syst.), respectively. The results at 0.9 TeV are in agreement with previous measurements and confirm the expectation of near equal hadron production in p-pbar and pp collisions. The results at 2.36 TeV represent the highest-energy measurements at a particle collider to date.
Measured differential yield of charged hadrons as a function of transverse momentum for pseudorapidities 0.1, 0.3, 0.5 and 0.7 for centre-of-mass energy 900 GeV.
Measured differential yield of charged hadrons as a function of transverse momentum for pseudorapidities 0.9, 1.1, 1.3 and 1.5 for centre-of-mass energy 900 GeV.
Measured differential yield of charged hadrons as a function of transverse momentum for pseudorapidities 1.7, 1.9, 2.1 and 2.3 for centre-of-mass energy 900 GeV.
A measurement of the underlying activity in scattering processes with transverse momentum scale in the GeV region is performed in proton-proton collisions at sqrt(s) = 0.9 TeV, using data collected by the CMS experiment at the LHC. Charged hadron production is studied with reference to the direction of a leading object, either a charged particle or a set of charged particles forming a jet. Predictions of several QCD-inspired models as implemented in PYTHIA are compared, after full detector simulation, to the data. The models generally predict too little production of charged hadrons with pseudorapidity eta < 2, p_T > 0.5 GeV/c, and azimuthal direction transverse to that of the leading object.
Average multiplicity of charged particles per unit of pseudorapidity as a function of pseudorapidity for events with leading track-jet transverse momenta > 1 and > 3 GeV. Statistical errors only.
Average scalar sum of the transverse momenta of charged particles per unit of pseusdorapidity and per radian as a function of DELTA(PHI) for events with leading track-jet transverse momenta > 1 and > 2 GeV. Statistical errors only. Typical systematic error of 1.8 PCT at a leading track-jet PT of 3.5 GeV.
The average multiplicity and average scalar sum of transverse momenta of charge particles per unit of pseudorapidity and per radian as a function of the leading track transverse momenta. Statistical errors only. Typical systematic error of 1.8 PCT at a leading track-jet PT of 3.5 GeV.
A search for emerging jets produced in proton-proton collisions at a center-of-mass energy of $13~\mathrm{TeV}$ is performed using data collected by the CMS experiment corresponding to an integrated luminosity of $138~\mathrm{fb}^{-1}$. This search examines a hypothetical dark quantum chromodynamics (QCD) sector that couples to the standard model (SM) through a scalar mediator. The scalar mediator decays into an SM quark and a dark sector quark. As the dark sector quark showers and hadronizes, it produces long-lived dark mesons that subsequently decay into SM particles, resulting in a jet, known as an emerging jet, with multiple displaced vertices. This search looks for pair production of the scalar mediator at the LHC, which yields events with two SM jets and two emerging jets at leading order. The results are interpreted using two dark sector models with different flavor structures, and exclude mediator masses up to 1950 (1800) GeV for an unflavored (flavor-aligned) dark QCD model.
Distribution of median of track $d_{xy}$ of CMS data, SM multijet MC events, and various signal samples. Events are required to pass the trigger requirements and also have 4 jets with $p_\mathrm{T}>100\mathrm{GeV}$. The distribution from various processes have their total count normalized to 1.
Distribution of $\alpha_{3D}$ with $D_{N}$ cutoff at 4 of CMS data, SM multijet MC events, and various signal samples. Events are required to pass the trigger requirements and also have 4 jets with $p_\mathrm{T}>100\mathrm{GeV}$. The distribution from various processes have their total count normalized to 1.
Distribution of Number of associated tracks with $d_{xy}>10^{-2.2}$ cm of CMS data, SM multijet MC events, and various signal samples. Events are required to pass the trigger requirements and also have 4 jets with $p_\mathrm{T}>100\mathrm{GeV}$. The distribution from various processes have their total count normalized to 1.
We report the results of a test of the compositeness of the heaviest charged lepton, $\tau$, using data collected in proton-proton collisions at a center of mass energy of 13 TeV at the Large Hadron Collider at CERN in 2016-2018, corresponding to an integrated luminosity of $138\,\mathrm{fb}^{-1}$. We seek tau lepton pair production in which one tau lepton is produced in an excited state and decays to a ground state tau lepton and photon. The analysis selects events with two isolated tau lepton decay candidates plus a high energy photon. The mass of the excited tau lepton is reconstructed using the missing transverse momentum in the event, assuming the momentum of the neutrinos from each tau lepton decay lie along the visible tau lepton decay product direction. We observe no excess of events above the standard model background prediction and use this null result to set lower bounds on the excited tau lepton mass. For a compositeness scale $\Lambda$ equal to the excited tau lepton mass (10 TeV), we exclude excited tau leptons with masses below 4700 GeV (2800 GeV).
Signal process cutflow for all taustar hypothesis masses, channels, and years. Cut descriptions: - numLeps : 1e0mu for ETau, 0e1mu For muTau, 0e0mu for TauTau - havePair : 1e + 1tauh for ETau, 1mu + 1tauh for MuTau, 2tauh for TauTau - trigger : passed appropriate high level trigger (HLT) for channel and year - m_vis : Visible mass of pair is >= 100 GeV - Zveto : No Z->ee or Z->mumu pairs - bveto : No btagged jets in event (only for ETau and MuTau) - gamma20GeV : have a photon with pt>20GeV - gamma100GeV : have a photon with pt>100GeV
Background-only-fit total covariance matrix for all channels and regions. Values are extracted from the Higgs Combine tool's fitDiagnostics option. Please see associated image ("fitRegions.pdf") for guide on region and channel setup.
Background-only-fit total covariance matrix for all channels and regions. Values are extracted from the Higgs Combine tool's fitDiagnostics option. Please see associated image ("fitRegions.pdf") for guide on region and channel setup.
A search is presented for the pair production of new heavy resonances, each decaying into a top quark or antiquark and a gluon. The analysis uses data recorded with the CMS detector from proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 $\text{fb}^{-1}$. Events with one muon or electron, multiple jets, and missing transverse momentum are selected. After using a deep neural network to enrich the data sample with signal-like events, distributions in the scalar sum of the transverse momenta of all reconstructed objects are analyzed in search for a signal. No significant deviations from the standard model predictions are found. Upper limits at $95\%$ confidence level are set on the product of cross section times branching fraction squared for the pair production of two excited top quarks in the $\mathrm{t}^{*} \to \mathrm{t}\mathrm{g}$ decay channel. The upper limits range from 0.12 pb to 0.8 fb for a $\text{t}^{*}$ with spin-1/2 and from 0.015 pb to 1.0 fb for a $\text{t}^{*}$ with spin-3/2. This corresponds to mass exclusion limits up to 1050 and 1700 GeV for spin-1/2 and spin-3/2 $\mathrm{t}^{*}$ particles, respectively.
Expected and observed 95% CL upper limits on the product of the $t^{*} \overline{t}^{*}$ production cross section and the branching fraction squared $BR^2(t^{*} \rightarrow tg)$ for a spin-1/2 $t^{*}$ as a function of $m_{t^{*}}$. The inner (green) and outer (yellow) bands give the central probability intervals containing 68 and 95% of the expected upper limits under the background-only hypothesis. The cross section predicted by theory, following an EFT approach, is shown in blue, assuming $BR(t^{*} \rightarrow tg)=1$.
Expected and observed 95% CL upper limits on the product of the $t^{*} \overline{t}^{*}$ production cross section and the branching fraction squared $BR^2(t^{*} \rightarrow tg)$ for a spin-3/2 $t^{*}$ as a function of $m_{t^{*}}$. The inner (green) and outer (yellow) bands give the central probability intervals containing 68 and 95% of the expected upper limits under the background-only hypothesis. The cross section predicted by theory, following an EFT approach, is shown in blue, assuming $BR(t^{*} \rightarrow tg)=1$. The results of the previous CMS analysis, using data corresponding to an integrated luminosity of 35.9 $fb^{-1}$, are shown in red.
Distributions in $S_T$ in the SR for the muon channel, after a background-only fit to the data. The signal distributions are scaled to the cross section predicted by the theory. The hatched bands show the post-fit uncertainty band, combining all sources of uncertainty. The ratio of data to the background predictions is shown in the panels below the distributions.
A search for Kaluza-Klein (KK) gluon resonances, $\mathrm{g_{KK}}$, decaying in cascade into two $\mathrm{W}$ bosons and a gluon via a scalar radion $\mathrm{R}$, $\mathrm{g_{KK} \rightarrow gR \rightarrow gWW}$, is presented. The final state with three large-radius jets, two of which contain the products of hadronically decaying $\mathrm{W}$ bosons is considered. The search is performed with $\sqrt{s}=13~\mathrm{TeV}$ proton-proton collision data collected by the CMS experiment at the CERN LHC during 2016-2018, corresponding to an integrated luminosity of $138~\mathrm{fb}^{-1}$. Both the $\mathrm{g_{KK}}$ and the $\mathrm{R}$ resonances are reconstructed. The ratio of their masses is used for event categorization, and the trijet mass distribution is used to extract a potential signal. Upper limits are set on the product of the $\mathrm{g_{KK}}$ production cross section and branching fraction to $\mathrm{gWW}$. Additionally, lower limits are set on the two resonance masses for an extended warped extra-dimensional model in which the quantum chromodynamics sector propagates into the extended bulk. This search is the first of its kind.
Figure 3 (upper left): The $m^∗_{jjj}$ postfit spectra in the SR1a. The lower panel shows the pull distribution.
Figure 3 (upper right): The $m^∗_{jjj}$ postfit spectra in the SR2a. The lower panel shows the pull distribution.
Figure 3 (middle left): The $m^∗_{jjj}$ postfit spectra in the SR3a. The lower panel shows the pull distribution.
Constraints on the Wilson coefficients (WCs) corresponding to dimension-six operators of the standard model effective field theory (SMEFT) are determined from a simultaneous fit to seven sets of CMS measurements probing Higgs boson, electroweak vector boson, top quark, and multi-jet production. The measurements of the electroweak precision observables at LEP and SLC are also included and provide complementary constraints to those from CMS. The CMS measurements, using $36$-$138\,\mathrm{fb}^{-1}$ of LHC proton-proton collision data at $\sqrt{s}=13\,\mathrm{TeV}$, are chosen to provide sensitivity to a broad set of operators, for which consistent SMEFT predictions can be derived. These are primarily measurements of differential cross sections or, in the case of Higgs boson production, simplified template cross sections, which are subsequently parametrized in the WCs. Measurements targeting $\mathrm{t\bar{t}X}$ production model the SMEFT effects directly in the reconstructed observables. Individual constraints on 64 WCs, and constraints on 42 linear combinations of WCs, are obtained. In the case of the linear combinations, the 42 parameters are varied simultaneously.
Expected and observed 95% CL limits on linear combinations of Wilson coefficients from the hybrid fit with the full set of input measurements.
Expected and observed individual 95% CL limits on Wilson coefficients from the hybrid fit with the full set of input measurements.
Rotation matrix obtained by performing the PCA on the Hessian matrix of the full set of measurements, including the t(t)X analysis.
Searches are performed for resonances decaying to two jets, with at least one jet originating from a b quark, in proton-proton collisions at $\sqrt{s}=13$ TeV. The dataset corresponds to an integrated luminosity of 137 fb$^{-1}$ collected by the CMS detector at the LHC. Jets are identified as containing energetic b hadrons using a deep neural network b tagger. The invariant mass spectrum of b-tagged dijets is well described by a smooth parameterization and no evidence for the production of new particles is observed. Cross-section upper limits are set on resonances decaying into b quarks. These limits exclude at $95\%$ confidence level models of Z' bosons with a mass less than 2.4 TeV, and an excited b quark with mass less than 4.0 TeV.
Signal shapes of b* from the process bg$\rightarrow$b∗$\rightarrow$bg. Shown are the wide jets used to reconstruct the dijet mass spectra.
The acceptance times efficiency of the event selection for a Z'$\rightarrow$bb resonance as a function of the resonance mass.
The differential cross sections as a function of the dijet mass for the double b tagging category during 2016.