Measurement of the associated production of a single top quark and a Z boson in pp collisions at $\sqrt{s} =$ 13 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Lett.B 779 (2018) 358-384, 2018.
Inspire Record 1642230 DOI 10.17182/hepdata.81680

A measurement is presented of the associated production of a single top quark and a Z boson. The study uses data from proton-proton collisions at $\sqrt{s} =$ 13 TeV recorded by the CMS experiment, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. Using final states with three leptons (electrons or muons), the tZq production cross section is measured to be $\sigma$(pp$\to$tZq$\to$Wb$\ell^+\ell^-$q) = $123 ^{+33}_{-31}$ (stat) $^{+29}_{-23}$ (syst) fb, where $\ell$ stands for electrons, muons, or $\tau$ leptons, with observed and expected significances of 3.7 and 3.1 standard deviations, respectively.

1 data table

The measured cross section, with statistical and systematic uncertainties. The observed significance. The expected significance


Search for new physics in final states with an energetic jet or a hadronically decaying W or Z boson and transverse momentum imbalance at $\sqrt{s} = $ 13 TeV

The CMS collaboration Sirunyan, A. M. ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Rev.D 97 (2018) 092005, 2018.
Inspire Record 1641762 DOI 10.17182/hepdata.80580

A search for new physics using events containing an imbalance in transverse momentum and one or more energetic jets arising from initial-state radiation or the hadronic decay of W or Z bosons is presented. A data sample of proton-proton collisions at $\sqrt{s} = $ 13 TeV, collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 35.9 fb$^{-1}$, is used. The observed data are found to be in agreement with the expectation from standard model processes. The results are interpreted as limits on the dark matter production cross section in simplified models with vector, axial-vector, scalar, and pseudoscalar mediators. Interpretations in the context of fermion portal and nonthermal dark matter models are also provided. In addition, the results are interpreted in terms of invisible decays of the Higgs boson and set stringent limits on the fundamental Planck scale in the Arkani-Hamed, Dimopoulos, and Dvali model with large extra spatial dimensions.

39 data tables

Comparison between data and MC simulation in the $\gamma$+jets control sample before and after performing the simultaneous fit across all the control samples and the signal region assuming the absence of any signal. The plot shows the monojet category. The hadronic recoil $p_{T}$ in $\gamma$+jets events is used as a proxy for $p_{T}^{miss}$ in the signal region. The last bin includes all events with hadronic recoil $p_{T}$ larger than 1250 GeV in the monojet category.

Comparison between data and MC simulation in the $\gamma$+jets control sample before and after performing the simultaneous fit across all the control samples and the signal region assuming the absence of any signal. The plot shows the mono-V category. The hadronic recoil $p_{T}$ in $\gamma$+jets events is used as a proxy for $p_{T}^{miss}$ in the signal region. The last bin includes all events with hadronic recoil $p_{T}$ larger than 750 GeV in the mono-V category.

Comparison between data and MC simulation in the dimuon control samples before and after performing the simultaneous fit across all the control samples and the signal region assuming the absence of any signal. Plot correspond to the monojet category. The hadronic recoil $p_{T}$ in dilepton events is used as a proxy for $p_{T}^{miss}$ in the signal region. The leading contribution is represented by Z+jets production. The other backgrounds include top quark, diboson, and W+jets processes.

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Constraints on the double-parton scattering cross section from same-sign W boson pair production in proton-proton collisions at $\sqrt{s} =$ 8 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
JHEP 02 (2018) 032, 2018.
Inspire Record 1641267 DOI 10.17182/hepdata.89148

A first search for same-sign WW production via double-parton scattering is performed based on proton-proton collision data at a center-of-mass energy of 8 TeV using dimuon and electron-muon final states. The search is based on the analysis of data corresponding to an integrated luminosity of 19.7 fb$^{-1}$. No significant excess of events is observed above the expected single-parton scattering yields. A 95% confidence level upper limit of 0.32 pb is set on the inclusive cross section for same-sign WW production via the double-parton scattering process. This upper limit is used to place a 95% confidence level lower limit of 12.2 mb on the effective double-parton cross section parameter, closely related to the transverse distribution of partons in the proton. This limit on the effective cross section is consistent with previous measurements as well as with Monte Carlo event generator predictions.

1 data table

Expected and observed upper limits on the cross section for inclusive same-sign WW production via DPS


Study of jet quenching with isolated-photon+jet correlations in PbPb and pp collisions at $\sqrt{s_{_{\mathrm{NN}}}} =$ 5.02 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Lett.B 785 (2018) 14-39, 2018.
Inspire Record 1638996 DOI 10.17182/hepdata.80815

Measurements of azimuthal angle and transverse momentum ($p_\mathrm{T}$) correlations of isolated photons and associated jets are reported for pp and PbPb collisions at $\sqrt{s_{_{\mathrm{NN}}}} =$ 5.02 TeV. The data were recorded with the CMS detector at the CERN LHC. For events containing a leading isolated photon with $p_\mathrm{T}^\gamma >$ 40 GeV$/c$ and an associated jet with $p_\mathrm{T}^\text{jet} >$ 30 GeV$/c$, the photon+jet azimuthal correlation and $p_\mathrm{T}$ imbalance in PbPb collisions are studied as functions of collision centrality and $p_\mathrm{T}^\gamma$. The results are compared to pp reference data collected at the same collision energy and to predictions from several theoretical models for parton energy loss. No evidence of broadening of the photon+jet azimuthal correlations is observed, while the ratio $p_\mathrm{T}^\text{jet}/p_\mathrm{T}^\gamma$ decreases significantly for PbPb data relative to the pp reference. All models considered agree within uncertainties with the data. The number of associated jets per photon with $p_\mathrm{T}^\gamma >$ 80 GeV$/c$ is observed to be shifted towards lower $p_\mathrm{T}^\text{jet}$ values in central PbPb collisions compared to pp collisions.

7 data tables

Jet resolution parameters for pp and PbPb collisions in various centrality bins.

The azimuthal correlation of photons and jets in five $p_{\mathrm{T}}^{\gamma}$ intervals for 0-30% and 30-100% centrality PbPb collisions. The smeared pp data are included for comparison.

Distribution of $x_{\mathrm{j}\gamma} = p_{\mathrm{T}}^{\mathrm{jet}} / p_{\mathrm{T}}^{\gamma}$ in five $p_{\mathrm{T}}^{\gamma}$ intervals for 0-30% and 30-100% centrality PbPb collisions. The smeared pp data are included for comparison. Empty bins are denoted as 'empty' in the table.

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Non-Gaussian elliptic-flow fluctuations in PbPb collisions at $\sqrt{\smash[b]{s_{_\text{NN}}}} = 5.02$ TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Lett.B 789 (2019) 643-665, 2019.
Inspire Record 1636197 DOI 10.17182/hepdata.80151

Event-by-event fluctuations in the elliptic-flow coefficient $v_2$ are studied in PbPb collisions at $\sqrt{s_{_\text{NN}}} = 5.02$ TeV using the CMS detector at the CERN LHC. Elliptic-flow probability distributions ${p}(v_2)$ for charged particles with transverse momentum 0.3$< p_\mathrm{T} <$3.0 GeV and pseudorapidity $| \eta | <$ 1.0 are determined for different collision centrality classes. The moments of the ${p}(v_2)$ distributions are used to calculate the $v_{2}$ coefficients based on cumulant orders 2, 4, 6, and 8. A rank ordering of the higher-order cumulant results and nonzero standardized skewness values obtained for the ${p}(v_2)$ distributions indicate non-Gaussian initial-state fluctuation behavior. Bessel-Gaussian and elliptic power fits to the flow distributions are studied to characterize the initial-state spatial anisotropy.

14 data tables

Unfolded elliptic flow probability density (p(v_2)) for 15-20\% collision centralities

Unfolded elliptic flow probability density (p(v_2)) for 30-35\% collision centralities

Unfolded elliptic flow probability density (p(v_2)) for 55-60\% collision centralities

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Search for diboson resonances in the 2$\ell$2$\nu$ final state

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
JHEP 03 (2018) 003, 2018.
Inspire Record 1635891 DOI 10.17182/hepdata.82124

A search for heavy resonances decaying to a pair of Z bosons is performed using data collected with the CMS detector at the LHC. Events are selected by requiring two oppositely charged leptons (electrons or muons), consistent with the decay of a Z boson, and large missing transverse momentum, which is interpreted as arising from the decay of a second Z boson to two neutrinos. The analysis uses data from proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The hypothesis of a spin-2 bulk graviton (X) decaying to a pair of Z bosons is examined for 600 $\le m_\mathrm{X} \le$ 2500 GeV and upper limits at 95% confidence level are set on the product of the production cross section and branching fraction of X $\to$ ZZ ranging from 100 to 4 fb. For bulk graviton models characterized by a curvature scale parameter $\tilde{k} =$ 0.5 in the extra dimension, the region $m_\mathrm{X} < $ 800 GeV is excluded, providing the most stringent limit reported to date. Variations of the model considering the possibility of a wide resonance produced exclusively via gluon-gluon fusion or $\mathrm{q}\overline{\mathrm{q}}$ annihilation are also examined.

11 data tables

The $p_T^Z$ distributions for electron channel comparing the data and background model with systematic uncertainty.

The $p_T^Z$ distributions for muon channel comparing the data and background model with systematic uncertainty.

The $p_T ^{miss}$ distributions for electron channel comparing the data and background model with systematic uncertainty.

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Measurement of the underlying event activity in inclusive Z boson production in proton-proton collisions at $\sqrt{s} = $ 13 TeV

The CMS collaboration Sirunyan, A.M. ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
JHEP 07 (2018) 032, 2018.
Inspire Record 1635889 DOI 10.17182/hepdata.80167

This paper presents a measurement of the underlying event activity in proton-proton collisions at a center-of-mass energy of 13 TeV, performed using inclusive Z boson production events collected with the CMS experiment at the LHC. The analyzed data correspond to an integrated luminosity of 2.1 fb$^{-1}$. The underlying event activity is quantified in terms of the charged particle multiplicity, as well as of the scalar sum of the charged particles' transverse momenta in different topological regions defined with respect to the Z boson direction. The distributions are unfolded to the stable particle level and compared with predictions from various Monte Carlo event generators, as well as with similar CDF and CMS measurements at center-of-mass energies of 1.96 and 7 TeV respectively.

6 data tables

Unfolded distributions of particle density in Z events, as a function of $p_{T}^{\mu\mu}$ in the towards ($\Delta\phi< 60^{\circ}$) region. Error bars represent the statistical and systematic uncertainties added in quadrature.

Unfolded distributions of particle density in Z events, as a function of $p_{T}^{\mu\mu}$ in the transverse ($60^{\circ} <\Delta\phi< 120^{\circ}$) region. Error bars represent the statistical and systematic uncertainties added in quadrature.

Unfolded distributions of particle density in Z events, as a function of $p_{T}^{\mu\mu}$ in the away ($\Delta\phi> 120^{\circ}$) region. Error bars represent the statistical and systematic uncertainties added in quadrature.

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Measurement of the inclusive $\mathrm{t}\overline{\mathrm{t}}$ cross section in pp collisions at $\sqrt{s} =$ 5.02 TeV using final states with at least one charged lepton

The CMS collaboration Sirunyan, A.M. ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
JHEP 03 (2018) 115, 2018.
Inspire Record 1635271 DOI 10.17182/hepdata.81690

The top quark pair production cross section ($\sigma_{\mathrm{t}\overline{\mathrm{t}}}$) is measured for the first time in pp collisions at a center-of-mass energy of 5.02 TeV. The data were collected by the CMS experiment at the LHC and correspond to an integrated luminosity of 27.4 pb$^{-1}$. The measurement is performed by analyzing events with at least one charged lepton. The measured cross section is $ \sigma_{\mathrm{t}\overline{\mathrm{t}}} = 69.5 \pm 6.1$ (stat) $\pm 5.6$ (syst) $\pm 1.6$ (lumi) pb, with a total relative uncertainty of 12%. The result is in agreement with the expectation from the standard model. The impact of the presented measurement on the determination of the gluon distribution function is investigated.

15 data tables

The measured fiducial cross sections in the $\ell$+jets and dilepton ($\rm{e}^\pm \mu^\mp$ or $\mu^\pm \mu^\mp$) decay channels. The first uncertainty is the statistical, the second is the systematic, and the last due to the integrated luminosity.

The measured total cross sections based on the $\ell$+jets (left), $\rm{e}^\pm \mu^\mp$ (middle) and $\mu^\pm \mu^\mp$ (right) decay channels. The first uncertainty is the statistical, the second is the systematic, and the last due to the integrated luminosity.

The measured total cross section in the combined $\ell$+jets and dilepton ($\rm{e}^\pm \mu^\mp$ or $\mu^\pm \mu^\mp$) decay channels. The weights of the individual measurements are 81.8% for $\ell$+jets, 13.5% for $\rm{e}^\pm \mu^\mp$, and 4.7% for $\mu^\pm \mu^\mp$ channels. The first uncertainty is the statistical, the second is the systematic, and the last due to the integrated luminosity.

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Measurement of associated Z + charm production in proton-proton collisions at $\sqrt{s} = $ 8 TeV

The CMS collaboration Sirunyan, A.M. ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Eur.Phys.J.C 78 (2018) 287, 2018.
Inspire Record 1634835 DOI 10.17182/hepdata.85868

A study of the associated production of a Z boson and a charm quark jet (Z + c), and a comparison to production with a b quark jet (Z + b), in pp collisions at a centre-of-mass energy of 8 TeV are presented. The analysis uses a data sample corresponding to an integrated luminosity of 19.7 fb$^{-1}$, collected with the CMS detector at the CERN LHC. The Z boson candidates are identified through their decays into pairs of electrons or muons. Jets originating from heavy flavour quarks are identified using semileptonic decays of c or b flavoured hadrons and hadronic decays of charm hadrons. The measurements are performed in the kinematic region with two leptons with $p_{\rm T}^{\ell} > $ 20 GeV, ${|\eta^{\ell}|} < $ 2.1, 71 $ < m_{\ell\ell} < $ 111 GeV, and heavy flavour jets with $p_{\rm T}^{{\rm jet}} > $ 25 GeV and ${|\eta^{{\rm jet}}|} < $ 2.5. The Z + c production cross section is measured to be $\sigma({\mathrm{p}}{\mathrm{p}} \rightarrow \mathrm{Z} + \mathrm{c} + \mathrm{X}) {\cal B}(\mathrm{Z} \rightarrow \ell^+\ell^-) = $ 8.8 $ \pm $ 0.5 (stat) $ \pm $ 0.6 (syst) pb. The ratio of the Z + c and Z + b production cross sections is measured to be $\sigma({\mathrm{p}}{\mathrm{p}} \rightarrow \mathrm{Z} + \mathrm{c} + \mathrm{X}) / \sigma({\mathrm{p}}{\mathrm{p}} \rightarrow \mathrm{Z} + \mathrm{b} + \mathrm{X}) = $ 2.0 $ \pm $ 0.2 (stat) $ \pm $ 0.2 (syst). The Z + c production cross section and the cross section ratio are also measured as a function of the transverse momentum of the Z boson and of the heavy flavour jet. The measurements are compared with theoretical predictions.

28 data tables

Signal yields N(Z+c) and N(Z+b), efficiency*acceptance correction factors C(Z+c) and C(Z+b), cross section sigma(Z+c)B and cross section ratios sigma(Z+c)/sigma(Z+b) in the three categories (semileptonic, D+-, D*) and in the two Z boson decay channels (e+e-, mu+mu-). The factors that correct the acceptance and selection inefficiencies are also given. They include the relevant branching fraction for the corresponding channel. All uncertainties quoted in the table are statistical, except for those of the measured cross sections and cross section ratios where the first uncertainty is statistical and the second is the estimated systematic uncertainty

Z+c and Z+b signal yields, differential cross section dsigma(Z+c)/dpTZ times branching ratio and differential cross sections ratio dsigma(Z+c)/dpTZ / dsigma(Z+b)/dpTZ for three ranges of the transverse momentum of the Z boson in the semileptonic mode

Z+c and Z+b signal yields, differential cross section dsigma(Z+c)/dpTZ times branching ratio and differential cross sections ratio dsigma(Z+c)/dpTZ / dsigma(Z+b)/dpTZ for three ranges of the transverse momentum of the jet in the semileptonic mode

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Search for top squarks and dark matter particles in opposite-charge dilepton final states at $\sqrt{s}=$ 13 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Rev.D 97 (2018) 032009, 2018.
Inspire Record 1634253 DOI 10.17182/hepdata.79809

A search for new physics is presented in final states with two oppositely charged leptons (electrons or muons), jets identified as originating from b quarks, and missing transverse momentum ($p_\mathrm{T}^\text{miss}$). The search uses proton-proton collision data at $\sqrt{s}=$ 13 TeV amounting to 35.9 fb$^{-1}$ of integrated luminosity collected using the CMS detector in 2016. Hypothetical signal events are efficiently separated from the dominant $\mathrm{t}\overline{\mathrm{t}}$ background with requirements on $p_\mathrm{T}^\text{miss}$ and transverse mass variables. No significant deviation is observed from the expected background. Exclusion limits are set in the context of simplified supersymmetric models with pair-produced top squarks. For top squarks, decaying exclusively to a top quark and a neutralino, exclusion limits are placed at 95% confidence level on the mass of the lightest top squark up to 800 GeV and on the lightest neutralino up to 360 GeV. These results, combined with searches in the single-lepton and all-jet final states, raise the exclusion limits up to 1050 GeV for the lightest top squark and up to 500 GeV for the lightest neutralino. For top squarks undergoing a cascade decay through charginos and sleptons, the mass limits reach up to 1300 GeV for top squarks and up to 800 GeV for the lightest neutralino. The results are also interpreted in a simplified model with a dark matter (DM) particle coupled to the top quark through a scalar or pseudoscalar mediator. For light DM, mediator masses up to 100 (50) GeV are excluded for scalar (pseudoscalar) mediators. The result for the scalar mediator achieves some of the most stringent limits to date in this model.

49 data tables

Figure 2 (left). Distribution of $M_{T2}(ll)$ in simulation after preselection and requiring $M_{T2}(ll) > 100$ GeV.

Figure 2 (center). Distribution of $M_{T2}(blbl)$ in simulation after preselection and requiring $M_{T2}(ll) > 100$ GeV.

Figure 2 (right). Distribution of $p_{T}^{miss}$ in simulation after preselection and requiring $M_{T2}(ll) > 100$ GeV.

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