Modifications of the properties of jets in PbPb collisions, relative to those in pp collisions, are studied at a nucleon-nucleon center-of-mass energy of $\sqrt{s_\mathrm{NN}} =$ 5.02 TeV via correlations of charged particles with the jet axis in relative pseudorapidity ($\Delta \eta$), relative azimuth ($\Delta \phi$), and relative angular distance from the jet axis $\Delta \mathrm{r} = \sqrt{{(\Delta\eta)^{2}+(\Delta\phi)^{2}}}$. This analysis uses data collected with the CMS detector at the LHC, corresponding to integrated luminosities of 404 $\mu$b$^{-1}$ and 27.4 pb$^{-1}$ for PbPb and pp collisions, respectively. Charged particle number densities, jet fragmentation functions, and jet shapes are presented as a function of PbPb collision centrality and charged-particle track transverse momentum, providing a differential description of jet modifications due to interactions with the quark-gluon plasma.
The distribution of jet-correlated charged-particle tracks with $|{\Delta\phi}|<1.0$ as a function of $\Delta\eta$ in pp and PbPb collisions. The PbPb results are shown for different centrality regions.
The difference between the PbPb and pp measurements from Table 1.
The distribution of jet-correlated charged-particle tracks with $|{\Delta\eta}|<1.0$ as a function of $\Delta\phi$ in pp and PbPb collisions. The PbPb results are shown for different centrality regions.
A search is presented for new high-mass resonances decaying into electron or muon pairs. The search uses proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the CMS experiment at the LHC in 2016, corresponding to an integrated luminosity of 36 fb$^{-1}$. Observations are in agreement with standard model expectations. Upper limits on the product of a new resonance production cross section and branching fraction to dileptons are calculated in a model-independent manner. This permits the interpretation of the limits in models predicting a narrow dielectron or dimuon resonance. A scan of different intrinsic width hypotheses is performed. Limits are set on the masses of various hypothetical particles. For the Z$'_\mathrm{SSM}$ (Z$'_{\psi}$) particle, which arises in the sequential standard model (superstring-inspired model), a lower mass limit of 4.50 (3.90) TeV is set at 95% confidence level. The lightest Kaluza-Klein graviton arising in the Randall-Sundrum model of extra dimensions, with coupling parameters $k/\overline{M}_\mathrm{Pl}$ of 0.01, 0.05, and 0.10, is excluded at 95% confidence level below 2.10, 3.65, and 4.25 TeV, respectively. In a simplified model of dark matter production via a vector or axial vector mediator, limits at 95% confidence level are obtained on the masses of the dark matter particle and its mediator.
The number of dielectron events in various invariant mass ranges. The total back- ground is the sum of the events for the SM processes listed. The yields from simulation are normalized relative to the expected cross sections, and overall the simulation is normalized to the observed yield using the number of events in the mass window 60-120 GeV. Uncertainties include both statistical and systematic components, summed in quadrature.
The number of dimuon events in various invariant mass ranges. The total back- ground is the sum of the events for the SM processes listed. The yields from simulation are normalized relative to the expected cross sections, and overall the simulation is normalized to the observed yield using the number of events in the mass window 60-120 GeV. Uncertainties include both statistical and systematic components, summed in quadrature.
The invariant mass spectra of dielectron events. The points with error bars represent the observed yield. The histogram represents the expectations from the SM processes. The bins have equal width in logarithmic scale so that the width in GeV becomes larger with increasing mass.
A search is presented for additional neutral Higgs bosons in the $\tau\tau$ final state in proton-proton collisions at the LHC. The search is performed in the context of the minimal supersymmetric extension of the standard model (MSSM), using the data collected with the CMS detector in 2016 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. To enhance the sensitivity to neutral MSSM Higgs bosons, the search includes production of the Higgs boson in association with b quarks. No significant deviation above the expected background is observed. Model-independent limits at 95% confidence level (CL) are set on the product of the branching fraction for the decay into $\tau$ leptons and the cross section for the production via gluon fusion or in association with b quarks. These limits range from 18 pb at 90 GeV to 3.5 fb at 3.2 TeV for gluon fusion and from 15 pb (at 90 GeV) to 2.5 fb (at 3.2 TeV) for production in association with b quarks, assuming a narrow width resonance. In the m$_{\text{h}}^{\text{mod+}}$ scenario these limits translate into a 95% CL exclusion of $\tan\beta>$ 6 for neutral Higgs boson masses below 250 GeV, where $\tan\beta$ is the ratio of the vacuum expectation values of the neutral components of the two Higgs doublets. The 95% CL exclusion contour reaches 1.6 TeV for $\tan\beta=$ 60.
Expected and observed 95% CL upper limits for the production of a single narrow resonance, $\phi$, with a mass between 90 GeV and 3.2 TeV via gluon-gluon fusion. This limit database corresponds to the values shown in Figure 7a of the paper.
Expected and observed 95% CL upper limits for the production of a single narrow resonance, $\phi$, with a mass between 90 GeV and 3.2 TeV in association with b-quarks. This limit database corresponds to the values shown in Figure 7b of the paper.
Scan of the likelihood function for the search in the $\tau\tau$ final state for a single narrow resonance, $\phi$, produced via gluon fusion ($gg\phi$) or in association with b quarks ($bb\phi$). The scan is performed in 40000 points of the ($\sigma(gg\phi)\cdot B(\phi\rightarrow\tau\tau)$, $\sigma(bb\phi)\cdot B(\phi\rightarrow\tau\tau)$) plane. An asimov dataset constructed from the expectation of all backgrounds and the SM Higgs boson is tested against a background hypothesis including the SM Higgs boson. For further details and instructions, please have a look into the following README file http://cms-results.web.cern.ch/cms-results/public-results/publications/HIG-17-020/2D-likelihood-scans/README.txt. Selected examples of such a likelihood scan are given in Figure 8 of the paper.
A search is presented for the associated production of a Higgs boson with a top quark pair in the all-jet final state. Events containing seven or more jets are selected from a sample of proton-proton collisions at $\sqrt{s} =$ 13 TeV collected with the CMS detector at the LHC in 2016, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. To separate the $\mathrm{t}\overline{\mathrm{t}}$H signal from the irreducible $\mathrm{t}\overline{\mathrm{t}}+\mathrm{b}\overline{\mathrm{b}}$ background, the analysis assigns leading order matrix element signal and background probability densities to each event. A likelihood-ratio statistic based on these probability densities is used to extract the signal. The results are provided in terms of an observed $\mathrm{t}\overline{\mathrm{t}}$H signal strength relative to the standard model production cross section $\mu=\sigma/\sigma_\mathrm{SM}$, assuming a Higgs boson mass of 125 GeV. The best fit value is $\hat{\mu} =$ 0.9 $\pm$ 0.7 (stat) $\pm$ 1.3 (syst) = 0.9 $\pm$ 1.5 (tot), and the observed and expected upper limits are, respectively, $\mu <$ 3.8 and $<$ 3.1 at 95% confidence levels.
Best fit values in the signal strength modifiers (mu), and their 68% CL intervals as split into the statistical and systematic components for each category and combinations of categories.
Values of log10(S/B), where S and B indicate the respective bin-by-bin yields of the signal and background expected in the MEM discriminant distributions, obtained from a combined fit with the constraint in the cross section of mu = 1.
A search is presented for physics beyond the standard model, based on measurements of dijet angular distributions in proton-proton collisions at $\sqrt{s}=$ 13 TeV. The data collected with the CMS detector at the LHC correspond to an integrated luminosity of 35.9 fb$^{-1}$. The observed distributions are found to be in agreement with predictions from perturbative quantum chromodynamics that include electroweak corrections. Constraints are placed on models containing quark contact interactions, extra spatial dimensions, quantum black holes, or dark matter using the detector-level distributions. In a benchmark model where only left-handed quarks participate, contact interactions are excluded at the 95% confidence level up to a scale of 12.8 or 17.5 TeV, for destructive or constructive interference, respectively. The most stringent lower limits to date are set on the ultraviolet cutoff in the Arkani-Hamed-Dimopoulos-Dvali model of extra dimensions. In the Giudice-Rattazzi-Wells convention, the cutoff scale is excluded up to 10.1 TeV. The production of quantum black holes is excluded for masses below 5.9 and 8.2 TeV, depending on the model. For the first time, lower limits between 2.0 and 4.6 TeV are set on the mass of a dark matter mediator for (axial-)vector mediators, for the universal quark coupling $g_\mathrm{q}\geq$ 1.
Normalized dijet angular distribution for events with dijet mass > 6.0 TeV.
Normalized dijet angular distribution for events with 5.4 < dijet mass < 6.0 TeV.
Normalized dijet angular distribution for events with 4.8 < dijet mass < 5.4 TeV.
Differential and double-differential cross sections for the production of top quark pairs in proton-proton collisions at $\sqrt{s} =$ 13 TeV are measured as a function of kinematic variables of the top quarks and the top quark-antiquark ($\mathrm{t}\overline{\mathrm{t}}$) system. In addition, kinematic variables and multiplicities of jets associated with the $\mathrm{t}\overline{\mathrm{t}}$ production are measured. This analysis is based on data collected by the CMS experiment at the LHC in 2016 corresponding to an integrated luminosity of 35.8 fb$^{-1}$. The measurements are performed in the lepton+jets decay channels with a single muon or electron and jets in the final state. The differential cross sections are presented at the particle level, within a phase space close to the experimental acceptance, and at the parton level in the full phase space. The results are compared to several standard model predictions that use different methods and approximations. The kinematic variables of the top quarks and the $\mathrm{t}\overline{\mathrm{t}}$ system are reasonably described in general, though none predict all the measured distributions. In particular, the transverse momentum distribution of the top quarks is more steeply falling than predicted. The kinematic distributions and multiplicities of jets are adequately modeled by certain combinations of next-to-leading-order calculations and parton shower models.
Absolute cross section at particle level as a function of $p_\text{T}(\text{t}_\text{h})$.
Covariance matrix of absolute cross section at particle level as a function of $p_\text{T}(\text{t}_\text{h})$.
Absolute cross section at particle level as a function of $|y(\text{t}_\text{h})|$.
A search has been performed for heavy resonances decaying to ZZ or ZW in 2$\ell$2q final states, with two charged leptons ($\ell=$ e,$\mu$) produced by the decay of a Z boson, and two quarks produced by the decay of a W or Z boson. The analysis is sensitive to resonances with masses in the range from 400 to 4500 GeV. Two categories are defined based on the merged or resolved reconstruction of the hadronically decaying vector boson, optimized for high- and low-mass resonances, respectively. The search is based on data collected during 2016 by the CMS experiment at the LHC in proton-proton collisions with a center-of-mass energy of $\sqrt{s}=$ 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. No excess is observed in the data above the standard model background expectation. Upper limits on the production cross section of heavy, narrow spin-1 and spin-2 resonances are derived as a function of the resonance mass, and exclusion limits on the production of W$'$ bosons and bulk graviton particles are calculated in the framework of the heavy vector triplet model and warped extra dimensions, respectively.
Distribution of the merged V candidate $\tau_{21}$, where the $\tau_{21}<$ 0.4 requirement has been removed, in data and simulation for events in the signal region of the low-mass analysis. The points show the data while the filled histograms show the background contributions. The gray band shows the statistical and systematic uncertainties in the background, while the dashed vertical region ("Higgs") shows the expected SM Higgs boson mass range, which is excluded from this analysis. A 600 GeV bulk graviton signal prediction is represented by the black dashed histogram; for visibility, the signal cross-section is increased by a factor of 5. The background normalization is derived from the final fit to the $m_{VZ}$ observable in data.
Distribution of the jet $p_{T}$ in data and simulation for events in the signal region of the low-mass analysis. The points show the data while the filled histograms show the background contributions. The gray band shows the statistical and systematic uncertainties in the background, while the dashed vertical region ("Higgs") shows the expected SM Higgs boson mass range, which is excluded from this analysis. A 600 GeV bulk graviton signal prediction is represented by the black dashed histogram; for visibility, the signal cross-section is increased by a factor of 5. The background normalization is derived from the final fit to the $m_{VZ}$ observable in data.
Distribution of V candidate $m_{j}$ in data and simulation for events in the signal regions of the low-mass search. The points show the data while the filled histograms show the background contributions. The gray band shows the statistical and systematic uncertainties in the background, while the dashed vertical region ("Higgs") shows the expected SM Higgs boson mass range, which is excluded from this analysis. A 600 GeV bulk graviton signal prediction is represented by the black dashed histogram; for visibility, the signal cross-section is increased by a factor of 5. The background normalization is derived from the final fit to the $m_{VZ}$ observable in data.
The observation of Higgs boson production in association with a top quark-antiquark pair is reported, based on a combined analysis of proton-proton collision data at center-of-mass energies of $\sqrt{s}=$ 7, 8, and 13 TeV, corresponding to integrated luminosities of up to 5.1, 19.7, and 35.9 fb$^{-1}$, respectively. The data were collected with the CMS detector at the CERN LHC. The results of statistically independent searches for Higgs bosons produced in conjunction with a top quark-antiquark pair and decaying to pairs of W bosons, Z bosons, photons, $\tau$ leptons, or bottom quark jets are combined to maximize sensitivity. An excess of events is observed, with a significance of 5.2 standard deviations, over the expectation from the background-only hypothesis. The corresponding expected significance from the standard model for a Higgs boson mass of 125.09 GeV is 4.2 standard deviations. The combined best fit signal strength normalized to the standard model prediction is 1.26 ${^{+0.31}_{-0.26}}$.
Best fit value of the ttH signal strength modifier $\mu_{\mathrm{ttH}}$, with its 1 and 2 standard deviation confidence intervals ($\sigma$), for the five individual decay channels considered, the combined result for 7+8 TeV alone and for 13 TeV alone, and the overall combined result. The Higgs boson mass is taken to be 125.09 GeV. For the $\mathrm{H}\rightarrow\mathrm{ZZ}$ decay mode, $\mu_{\mathrm{ttH}}$ is constrained to be positive to prevent the corresponding event yield from becoming negative. The SM expectation is shown as a dashed vertical line.
Best fit value, with its uncertainty, of the ttH signal strength modifier $\mu_{\mathrm{ttH}}$, for the five individual decay channels considered, the combined result for 7+8 TeV alone and for 13 TeV alone, and the overall combined result. The total uncertainties are decomposed into their statistical (Stat), experimental systematic (Expt), background theory systematic (Thbgd), and signal theory systematic (Thsig) components.
Distribution of events as a function of the decimal logarithm of S/B, where S and B are the expected post-fit signal (with $\mu_{\mathrm{ttH}}$ = 1) and background yields, respectively, in each bin of the distributions considered in this combination. The shaded histogram shows the expected background distribution. The two hatched histograms, each stacked on top of the background histogram, show the signal expectation for the SM ($\mu_{\mathrm{ttH}}$ = 1) and the observed ($\mu_{\mathrm{ttH}}$ = 1.26) signal strengths.
The production of a Z boson, decaying to two charged leptons, in association with jets in proton-proton collisions at a centre-of-mass energy of 13 TeV is measured. Data recorded with the CMS detector at the LHC are used that correspond to an integrated luminosity of 2.19 fb$^{-1}$. The cross section is measured as a function of the jet multiplicity and its dependence on the transverse momentum of the Z boson, the jet kinematic variables (transverse momentum and rapidity), the scalar sum of the jet momenta, which quantifies the hadronic activity, and the balance in transverse momentum between the reconstructed jet recoil and the Z boson. The measurements are compared with predictions from four different calculations. The first two merge matrix elements with different parton multiplicities in the final state and parton showering, one of which includes one-loop corrections. The third is a fixed-order calculation with next-to-next-to-leading order accuracy for the process with a Z boson and one parton in the final state. The fourth combines the fully differential next-to-next-to-leading order calculation with next-to-next-to-leading logarithm resummation and parton showering.
Measured cross section for Z+jets as a function of the exclusive jet multiplicity, $N_{\text{jets}}$, and breakdown of the relative uncertainty.
Bin-to-bin correlation in the measured cross section for Z+jets as a function of the exclusive jet multiplicity, $N_{\text{jets}}$.
Measured cross section for Z+jets as a function of inclusive jet multiplicity, $N_{\text{jets}}^{\text{min}}$, and breakdown of the relative uncertainty.
A search is presented for long-lived charged particles that decay within the CMS detector and produce the signature of a disappearing track. A disappearing track is an isolated track with missing hits in the outer layers of the silicon tracker, little or no energy in associated calorimeter deposits, and no associated hits in the muon detectors. This search uses data collected with the CMS detector in 2015 and 2016 from proton-proton collisions at a center-of-mass energy of 13 TeV at the LHC, corresponding to an integrated luminosity of 38.4 fb$^{-1}$. The results of the search are interpreted in the context of the anomaly-mediated supersymmetry breaking model. The data are consistent with the background-only hypothesis. Limits are set on the product of the cross section for direct production of charginos and their branching fraction to a neutralino and a pion, as a function of the chargino mass and lifetime. At 95% confidence level, charginos with masses below 715 (695) GeV are excluded for a lifetime of 3 (7) ns, as are charginos with lifetimes from 0.5 to 60 ns for a mass of 505 GeV. These are the most stringent limits using a disappearing track signature on this signal model for chargino lifetimes above $\approx$ 0.7 ns.
The expected and observed 95% CL upper limits on the product of the cross section for direct production of charginos and their branching fraction to $\widetilde{\chi}^{0}_{1}\mathrm{\pi^{\pm}}$ as a function of chargino mass for a chargino lifetime of 0.3 ns. The ratio of the vacuum expectation values of the two Higgs doublets, $\tan \beta$, is fixed to 5 with $\mu > 0$, where $\mu$ is the higgsino mass parameter. The direct chargino production cross section includes both $\widetilde{\chi}^{0}_{1}\widetilde{\chi}^\pm_{1}$ and $\widetilde{\chi}^\pm_{1}\widetilde{\chi}^\mp_{1}$ production in roughly a 2:1 ratio for all chargino masses considered, and the branching fraction of $\widetilde{\chi}^\pm_{1} \rightarrow \widetilde{\chi}^{0}_{1}\mathrm{\pi^{\pm}}$ is set to 100%. The theoretical prediction for the AMSB model is also shown.
The expected and observed 95% CL upper limits on the product of the cross section for direct production of charginos and their branching fraction to $\widetilde{\chi}^{0}_{1}\mathrm{\pi^{\pm}}$ as a function of chargino mass for a chargino lifetime of 3.3 ns. The ratio of the vacuum expectation values of the two Higgs doublets, $\tan \beta$, is fixed to 5 with $\mu > 0$, where $\mu$ is the higgsino mass parameter. The direct chargino production cross section includes both $\widetilde{\chi}^{0}_{1}\widetilde{\chi}^\pm_{1}$ and $\widetilde{\chi}^\pm_{1}\widetilde{\chi}^\mp_{1}$ production in roughly a 2:1 ratio for all chargino masses considered, and the branching fraction of $\widetilde{\chi}^\pm_{1} \rightarrow \widetilde{\chi}^{0}_{1}\mathrm{\pi^{\pm}}$ is set to 100%. The theoretical prediction for the AMSB model is also shown.
The expected and observed 95% CL upper limits on the product of the cross section for direct production of charginos and their branching fraction to $\widetilde{\chi}^{0}_{1}\mathrm{\pi^{\pm}}$ as a function of chargino mass for a chargino lifetime of 33 ns. The ratio of the vacuum expectation values of the two Higgs doublets, $\tan \beta$, is fixed to 5 with $\mu > 0$, where $\mu$ is the higgsino mass parameter. The direct chargino production cross section includes both $\widetilde{\chi}^{0}_{1}\widetilde{\chi}^\pm_{1}$ and $\widetilde{\chi}^\pm_{1}\widetilde{\chi}^\mp_{1}$ production in roughly a 2:1 ratio for all chargino masses considered, and the branching fraction of $\widetilde{\chi}^\pm_{1} \rightarrow \widetilde{\chi}^{0}_{1}\mathrm{\pi^{\pm}}$ is set to 100%. The theoretical prediction for the AMSB model is also shown.