Double-parton scattering is investigated using events with a Z boson and jets. The Z boson is reconstructed using only the dimuon channel. The measurements are performed with proton-proton collision data recorded by the CMS experiment at the LHC at $\sqrt{s} =$ 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$ collected in the year 2016. Differential cross sections of Z + $\geq$ 1 jet and Z + $\geq$ 2 jets are measured with transverse momentum of the jets above 20 GeV and pseudorapidity $|\eta|$$\lt$ 2.4. Several distributions with sensitivity to double-parton scattering effects are measured as functions of the angle and the transverse momentum imbalance between the Z boson and the jets. The measured distributions are compared with predictions from several event generators with different hadronization models and different parameter settings for multiparton interactions. The measured distributions show a dependence on the hadronization and multiparton interaction simulation parameters, and are important input for future improvements of the simulations.
Differential cross sections as function of Delta Phi between Z boson and the leading jet for Z+ ≥ 1 jet events.
Differential cross sections as function of transverse momentum imbalance between Z boson and the leading jet for Z+ ≥ 1 jet events.
Differential cross sections as function of Delta Phi between Z boson and dijet for Z+ ≥ 2 jets events.
A search for a heavy Higgs boson H decaying into the observed Higgs boson h with a mass of 125 GeV and another Higgs boson h$_\mathrm{S}$ is presented. The h and h$_\mathrm{S}$ bosons are required to decay into a pair of tau leptons and a pair of b quarks, respectively. The search uses a sample of proton-proton collisions collected with the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 137 fb$^{-1}$. Mass ranges of 240-3000 GeV for $m_\mathrm{H}$ and 60-2800 GeV for $m_\mathrm{h_S}$ are explored in the search. No signal has been observed. Model independent 95% confidence level upper limits on the product of the production cross section and the branching fractions of the signal process are set with a sensitivity ranging from 125 fb (for $m_\mathrm{H}$ $=$ 240 GeV) to 2.7 fb (for $m_\mathrm{H}$ $=$ 1000 GeV). These limits are compared to maximally allowed products of the production cross section and the branching fractions of the signal process in the next-to-minimal supersymmetric extension of the standard model.
Expected and observed exclusion limits for heavy higgs boson mass 240 GeV
Expected and observed exclusion limits for heavy higgs boson mass 280 GeV
Expected and observed exclusion limits for heavy higgs boson mass 320 GeV
A search for W$\gamma$ resonances in the mass range between 0.7 and 6.0 TeV is presented. The W boson is reconstructed via its hadronic decays, with the final-state products forming a single large-radius jet, owing to a high Lorentz boost of the W boson. The search is based on proton-proton collision data at $\sqrt{s} =$ 13 TeV, corresponding to an integrated luminosity of 137 fb$^{-1}$, collected with the CMS detector at the LHC in 2016-2018. The W$\gamma$ mass spectrum is parameterized with a smoothly falling background function and examined for the presence of resonance-like signals. No significant excess above the predicted background is observed. Model-specific upper limits at 95% confidence level on the product of the cross section and branching fraction to the W$\gamma$ channel are set. Limits for narrow resonances and for resonances with an intrinsic width equal to 5% of their mass, for spin-0 and spin-1 hypotheses, range between 0.17 fb at 6.0 TeV and 55 fb at 0.7 TeV. These are the most restrictive limits to date on the existence of such resonances over a large range of probed masses. In specific heavy scalar (vector) triplet benchmark models, narrow resonances with masses between 0.75 (1.15) and 1.40 (1.36) TeV are excluded for a range of model parameters. Model-independent limits on the product of the cross section, signal acceptance, and branching fraction to the W$\gamma$ channel are set for minimum W$\gamma$ mass thresholds between 1.5 and 8.0 TeV.
Fitted 4th order polynomials to the signal acceptance for narrow and broad, scalar and vector Wgamma resonances. This quantity is defined as the ratio between the number of signal events falling within the analysis acceptance at the generator level to the number of signal events generated. The fitting function is $ A = p0 + p1*m + p2*m^2 + p3*m^3 + p4*m^4$, where $ A$ is the acceptance and m is the signal mass.
Fitted 4th order polynomials to the signal acceptance for narrow and broad, scalar and vector Wgamma resonances. This quantity is defined as the ratio between the number of signal events falling within the analysis acceptance at the generator level to the number of signal events generated. The fitting function is $ A = p0 + p1*m + p2*m^2 + p3*m^3 + p4*m^4$, where $ A$ is the acceptance and m is the signal mass.
Fitted 4th order polynomials to the product of the signal efficiency and acceptance for narrow and broad, scalar and vector Wgamma resonances. This quantity is defined as the ratio between the number of signal events passing full analysis cuts to the number of signal events generated. The fitting function is $ A \epsilon = p0 + p1*m + p2*m^2 + p3*m^3 + p4*m^4$, where $ A \epsilon$ is the product of the signal efficiency and acceptance, m is the signal mass.
The first observation of the electroweak (EW) production of a Z boson, a photon, and two forward jets (Z$\gamma$jj) in proton-proton collisions at a center-of-mass energy of 13 TeV is presented. A data set corresponding to an integrated luminosity of 137 fb$^{-1}$, collected by the CMS experiment at the LHC in 2016-2018 is used. The measured fiducial cross section for EW Z$\gamma$jj is $\sigma_{\mathrm{EW}}$ = 5.21 $\pm$ 0.52 (stat) $\pm$ 0.56 (syst) fb = 5.21 $\pm$ 0.76 fb. Single-differential cross sections in photon, leading lepton, and leading jet transverse momenta, and double-differential cross sections in $m_{\mathrm{jj}}$ and $\lvert\Delta\eta_{\mathrm{jj}}\rvert$ are also measured. Exclusion limits on anomalous quartic gauge couplings are derived at 95% confidence level in terms of the effective field theory operators $\mathrm{M}_{0}$ to $\mathrm{M}_{5}$, $\mathrm{M}_{7}$, $\mathrm{T}_{0}$ to $\mathrm{T}_{2}$, and $\mathrm{T}_{5}$ to $\mathrm{T}_{9}$.
The measured inclusive fiducial cross section for the pure electroweak Z$\gamma$jj production. The uncertainty of the observed results includes the stastical uncertianty and the systematic uncertainty, while the uncertainty of the predicted results is the theoretical uncertainty from the MadGraph5_aMC@NLO.
The measured inclusive fiducial cross section for the combined QCD-induced and electroweak Z$\gamma$jj production. The uncertainty of the observed results includes the stastical uncertianty and the systematic uncertainty, while the uncertainty of the predicted results is the theoretical uncertainty from the MadGraph5_aMC@NLO.
The measured single-differential cross sections in photon transverse momenta for the pure electroweak Z$\gamma$jj production. The total uncertainty of the observed results includes the stastical uncertianty and the systematic uncertainty, while the uncertainty of the predicted results is the theoretical uncertainty from the MadGraph5_aMC@NLO. The last bin includes overflow events.
Jets containing a prompt J$/\psi$ meson are studied in lead-lead collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV, using the CMS detector at the LHC. Jets are selected to be in the transverse momentum range of 30 $\lt$$p_\mathrm{T}$$\lt$ 40 GeV. The J$/\psi$ yield in these jets is evaluated as a function of the jet fragmentation variable $z$, the ratio of the J$/\psi$$p_\mathrm{T} $ to the jet $p_\mathrm{T}$. The nuclear modification factor, $R_\mathrm{AA}$, is then derived by comparing the yield in lead-lead collisions to the corresponding expectation based on proton-proton data, at the same nucleon-nucleon center-of-mass energy. The suppression of the J$/\psi$ yield shows a dependence on $z$, indicating that the interaction of the J$/\psi$ with the quark-gluon plasma formed in heavy ion collisions depends on the fragmentation that gives rise to the J$/\psi$ meson.
Normalized $z$ distribution in pp collisions.
The J/$\psi$ differential cross section in pp and the $T_{AA}$-scaled yield in PbPb collisions, as a function of $z$.
The nuclear modification factor R$_{\rm AA}$, as a function of $z$.
The first measurements of diboson production cross sections in proton-proton interactions at a center-of-mass energy of 5.02 TeV are reported. They are based on data collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 302 pb$^{-1}$. Events with two, three, or four charged light leptons (electrons or muons) in the final state are analyzed. The WW, WZ, and ZZ total cross sections are measured as $\sigma_\mathrm{WW} =$ 37.0 $^{+5.5}_{-5.2}$ (stat) $^{+2.7}_{-2.6}$ (syst) pb, $\sigma_\mathrm{WZ} =$ 6.4 $^{+2.5}_{-2.1}$ (stat) $^{+0.5}_{-0.3}$ (syst) pb, and $\sigma_\mathrm{ZZ} =$ 5.3 $^{+2.5}_{-2.1}$ (stat) $^{+0.5}_{-0.4}$ (syst) pb. All measurements are in good agreement with theoretical calculations at combined next-to-next-to-leading order quantum chromodynamics and next-to-leading order electroweak accuracy.
Expected event yields in the WW SR and observed number of events. The uncertainties correspond to the statistical and systematic component, respectively.
Expected event yields for the signal and total background in the WZ and ZZ SRs, and observed number of events. The uncertainties correspond to the statistical and systematic component, respectively.
Distribution of the dilepton pT in the WW signal region. Events from DY, conversions, and diboson processes are grouped into the 'Others' category. The vertical error bars represent the statistical uncertainty in the data and the shaded band the uncertainty in the prediction. The signal contributions are scaled to the measured cross sections (postfit).
The production cross sections for prompt open-charm mesons in proton-proton collisions at a center-of-mass energy of 13 TeV are reported. The measurement is performed using a data sample collected by the CMS experiment corresponding to an integrated luminosity of 29 nb$^{-1}$. The differential production cross sections of the D$^{*\pm}$, D$^\pm$, and D$^0$ ($\overline{\mathrm{D}}^{0}$) mesons are presented in ranges of transverse momentum and pseudorapidity 4 $\lt$$p_\mathrm{T}$$\lt$ 100 GeV and $\lvert\eta\rvert$$\lt$ 2.1, respectively. The results are compared to several theoretical calculations and to previous measurements.
The differential cross sections of prompt D^{*+} plus D^{*-}, D0 + bar{D0}, and D+ + D-production in pT bins with |eta| < 2.1;the first uncertainty is statistical, the second is systematic.
The differential cross sections of prompt D^{*+} plus D^{*-}, D0 + bar{D0}, and D+ + D-production in |eta| bins with 4 < pT < 100 GeV;the first uncertainty is statistical, the second is systematic.
The production cross section of a top quark pair in association with a photon is measured in proton-proton collisions at a center-of-mass energy of 13 TeV. The data set, corresponding to an integrated luminosity of 137 fb$^{-1}$, was recorded by the CMS experiment during the 2016-2018 data taking of the LHC. The measurements are performed in a fiducial volume defined at the particle level. Events with an isolated, highly energetic lepton, at least three jets from the hadronization of quarks, among which at least one is b tagged, and one isolated photon are selected. The inclusive fiducial $\mathrm{t\overline{t}}\gamma$ cross section, for a photon with transverse momentum greater than 20 GeV and pseudorapidity $\lvert \eta\rvert$$\lt$ 1.4442, is measured to be 798 $\pm$ 7 (stat) $\pm$ 48 (syst) fb, in good agreement with the prediction from the standard model at next-to-leading order in quantum chromodynamics. The differential cross sections are also measured as a function of several kinematic observables and interpreted in the framework of the standard model effective field theory (EFT), leading to the most stringent direct limits to date on anomalous electromagnetic dipole moment interactions of the top quark and the photon.
Distribution of $p_{T}(\gamma)$ in the $N_{jet}\geq 3$ signal region.
Distribution of $p_{T}(\gamma)$ in the $N_{jet}\geq 3$ signal region.
Distribution of $m_{T}(W)$ in the $N_{jet}\geq 3$ signal region.
A search for long-lived particles (LLPs) produced in decays of standard model (SM) Higgs bosons is presented. The data sample consists of 137 fb$^{-1}$ of proton-proton collisions at $\sqrt{s} =$ 13 TeV, recorded at the LHC in 2016-2018. A novel technique is employed to reconstruct decays of LLPs in the endcap muon detectors. The search is sensitive to a broad range of LLP decay modes and to masses as low as a few GeV. No excess of events above the SM background is observed. The most stringent limits to date on the branching fraction of the Higgs boson to LLPs subsequently decaying to quarks and $\tau^+\tau^-$ are found for proper decay lengths greater than 6, 20, and 40 m, for LLP masses of 7, 15, and 40 GeV, respectively.
The 95% CL observed and expected limits on the branching fraction B(H $\rightarrow$ SS) for 7 GeV mass and $ S \rightarrow d\bar{d}$ decay mode.
The 95% CL observed and expected limits on the branching fraction B(H $\rightarrow$ SS) for 7 GeV mass and $ S \rightarrow d\bar{d}$ decay mode.
The 95% CL observed and expected limits on the branching fraction B(H $\rightarrow$ SS) for 15 GeV mass and $ S \rightarrow d\bar{d}$ decay mode.
A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb$^{-1}$ collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on the model, the combined result excludes a top squark mass up to 1325 GeV for a massless neutralino, and a neutralino mass up to 700 GeV for a top squark mass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV.
Leading lepton ${p}_{T}$ distribution of data and MC events in the signal region with the signal stacked on top of the background prediction for a mass hypothesis of ${m}_{stop} = 225GeV$ and ${m}_{LSP} = 50 GeV$. Events from ttW, ttZ, DY, non-prompt leptons, and diboson processes are grouped into the 'Other' category. The lower panel contains the data-to-prediction ratio. The uncertainty band includes statistical, background normalization and all systematic uncertainties.
${m}_{T2}$ distribution of data and MC events in the signal region with the signal stacked on top of the background prediction for a mass hypothesis of ${m}_{stop} = 225GeV$ and ${m}_{LSP} = 50 GeV$. Events from ttW, ttZ, DY, non-prompt leptons, and diboson processes are grouped into the 'Other' category. The lower panel contains the data-to-prediction ratio. The uncertainty band includes statistical, background normalization and all systematic uncertainties.
${H}_{T}$ distribution of data and MC events in the signal region with the signal stacked on top of the background prediction for a mass hypothesis of ${m}_{stop} = 225GeV$ and ${m}_{LSP} = 50 GeV$. Events from ttW, ttZ, DY, non-prompt leptons, and diboson processes are grouped into the 'Other' category. The lower panel contains the data-to-prediction ratio. The uncertainty band includes statistical, background normalization and all systematic uncertainties.
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