A search for the production of pairs of heavy Majorana neutrinos (N$_\ell$) from the decays of Z' bosons is performed using the CMS detector at the LHC. The data were collected in proton-proton collisions at a center-of-mass energy of $\sqrt{s}$ = 13 TeV, with an integrated luminosity of 138 fb$^{-1}$. The signature for the search is an excess in the invariant mass distribution of the final-state objects, two same-flavor leptons (e or $\mu$) and at least two jets. No significant excess of events beyond the expected background is observed. Upper limits at 95% confidence level are set on the product of the Z' production cross section and its branching fraction to a pair of N$_\ell$, as functions of N$_\ell$ and Z' boson masses ($m_{\mathrm{N}_\ell}$ and $m_\mathrm{Z'}$, respectively) for $m_\mathrm{Z'}$ from 0.4 to 4.6 TeV and $m_{\mathrm{N}_\ell}$ from 0.1 TeV to $m_\mathrm{Z'}$/2. In the theoretical framework of a left-right symmetric model, exclusion bounds in the $m_{\mathrm{N}_\ell}-m_\mathrm{Z'}$ plane are presented in both the electron and muon channels. The observed upper limit on $m_\mathrm{Z'}$ reaches up to 4.42 TeV. These are the most restrictive limits to date on the mass of N$_\ell$ as a function of the Z' boson mass.
Reconstructed mass of the Z' candidate in CR1, which consists of flavor sidebands of SR1 (upper), SR2 (middle), and SR3 (lower) regions. Pre-fit (post-fit) results are shown on the left (right). The fitting procedure is described in Section 7.
Reconstructed mass of the Z' candidate in CR1, which consists of flavor sidebands of SR1 (upper), SR2 (middle), and SR3 (lower) regions. Pre-fit (post-fit) results are shown on the left (right). The fitting procedure is described in Section 7.
Reconstructed mass of the Z' candidate in CR1, which consists of flavor sidebands of SR1 (upper), SR2 (middle), and SR3 (lower) regions. Pre-fit (post-fit) results are shown on the left (right). The fitting procedure is described in Section 7.
The second-order ($v_2$) and third-order ($v_3$) Fourier coefficients describing the azimuthal anisotropy of prompt and nonprompt (from b-hadron decays) J/$\psi$, as well as prompt $\psi$(2S) mesons are measured in lead-lead collisions at a center-of-mass energy per nucleon pair of $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV. The analysis uses a data set corresponding to an integrated luminosity of 1.61 nb$^{-1}$ recorded with the CMS detector. The J/$\psi$ and $\psi$(2S) mesons are reconstructed using their dimuon decay channel. The $v_2$ and $v_3$ coefficients are extracted using the scalar product method and studied as functions of meson transverse momentum and collision centrality. The measured $v_2$ values for prompt J/$\psi$ mesons are found to be larger than those for nonprompt J/$\psi$ mesons. The prompt J/$\psi$$v_2$ values at high $p_\mathrm{T}$ are found to be underpredicted by a model incorporating only parton energy loss effects in a quark-gluon plasma medium. Prompt and nonprompt J/$\psi$ meson $v_3$ and prompt $\psi$(2S) $v_2$ and $v_3$ values are also reported for the first time, providing new information about heavy quark interactions in the hot and dense medium created in heavy ion collisions.
The $v_{2}$ values as functions of $p_{\text{T}}$ for prompt and nonprompt J/$\psi$ mesons in the 10–60% centrality range. The results for 3 $< p_{\text{T}} <$ 6.5 and 6.5 $< p_{\text{T}} <$ 50 GeV/c are studied in the rapidity range of 1.6 $< |y| <$ 2.4 and $|y| <$ 2.4, respectively.
The $v_{2}$ values as a function of centrality for prompt and nonprompt J/$\psi$ mesons. The kinematic range is 6.5 $< p_{\text{T}} <$ 50 GeV/c and $|y| <$ 2.4.
The $v_{3}$ values as functions of $p_{\text{T}}$ for prompt and nonprompt J/$\psi$ mesons in the 10–60% centrality range. The results for 3 $< p_{\text{T}} <$ 6.5 and 6.5 $< p_{\text{T}} <$ 50 GeV/c are studied in the rapidity range of 1.6 $< |y| <$ 2.4 and $|y| <$ 2.4, respectively.
The production of $\Upsilon$(2S) and $\Upsilon$(3S) mesons in lead-lead (PbPb) and proton-proton (pp) collisions is studied in their dimuon decay channel using the CMS detector at the LHC. The $\Upsilon$(3S) meson is observed for the first time in PbPb collisions, with a significance above five standard deviations. The ratios of yields measured in PbPb and pp collisions are reported for both the $\Upsilon$(2S) and $\Upsilon$(3S) mesons, as functions of transverse momentum and PbPb collision centrality. These ratios, when appropriately scaled, are significantly less than unity, indicating a suppression of $\Upsilon$ yields in PbPb collisions. This suppression increases from peripheral to central PbPb collisions. Furthermore, the suppression is stronger for $\Upsilon$(3S) mesons compared to $\Upsilon$(2S) mesons, extending the pattern of sequential suppression of quarkonium states in nuclear collisions previously seen for the $\psi$/J, $\psi$(2S), $\Upsilon$(1S), and $\Upsilon$(2S) mesons.
Measured $R_\text{AA}$ for the $\Upsilon(2S)$ state as functions of PbPb collision centrality, integrated over the full kinematic range $p_\text{T}$ < 30 GeV/c and |y| < 2.4. The global uncertainty "PP MB" represents the pp luminosity and PbPb $N_\text{MB}$ combined uncertainties, whereas the global uncertainty "PP 2S" corresponds to the uncertainty on the $\Upsilon(2S)$ pp yields.
Measured $R_\text{AA}$ for the $\Upsilon(2S)$ state as functions of PbPb collision centrality, integrated over the full kinematic range $p_\text{T}$ < 30 GeV/c and |y| < 2.4. The global uncertainty "PP MB" represents the pp luminosity and PbPb $N_\text{MB}$ combined uncertainties, whereas the global uncertainty "PP 2S" corresponds to the uncertainty on the $\Upsilon(2S)$ pp yields.
Measured $R_\text{AA}$ for the $\Upsilon(3S)$ state as functions of PbPb collision centrality, integrated over the full kinematic range $p_\text{T}$ < 30 GeV/c and |y| < 2.4. The global uncertainty "PP MB" represents the pp luminosity and PbPb $N_\text{MB}$ combined uncertainties, whereas the global uncertainty "PP 3S" corresponds to the uncertainty on the $\Upsilon(3S)$ pp yields.
A generic search is presented for the associated production of a Z boson or a photon with an additional unspecified massive particle X, pp $\to$ pp + Z/$\gamma$ + X, in proton-tagged events from proton-proton collisions at $\sqrt{s}$ = 13 TeV, recorded in 2017 with the CMS detector and the CMS-TOTEM precision proton spectrometer. The missing mass spectrum is analysed in the 600-1600 GeV range and a fit is performed to search for possible deviations from the background expectation. No significant excess in data with respect to the background predictions has been observed. Model-independent upper limits on the visible production cross section of pp $\to$ pp + Z/$\gamma$ + X are set.
Comparison of the $m_{miss}$ shapes for the simulated signal events within the fiducial region and those outside it, after including the effect of PU protons as describe in the text, for a generated $m_{X}$ mass of 1000 GeV. The distributions are shown for multi(+z)-multi(−z) proton reconstruction categories.
Comparison of the $m_{miss}$ shapes for the simulated signal events within the fiducial region and those outside it, after including the effect of PU protons as describe in the text, for a generated $m_{X}$ mass of 1000 GeV. The distributions are shown for multi(+z)-single(−z) proton reconstruction categories.
Comparison of the $m_{miss}$ shapes for the simulated signal events within the fiducial region and those outside it, after including the effect of PU protons as describe in the text, for a generated $m_{X}$ mass of 1000 GeV. The distributions are shown for single(+z)-multi(−z) proton reconstruction categories.
A search for the electroweak production of a vector-like quark T$'$, decaying to a top quark and a Higgs boson is presented. The search is based on a sample of proton-proton collision events recorded at the LHC at $\sqrt{s}$ = 13 TeV, corresponding to an integrated luminosity of 138 fb$^{-1}$. This is the first T$'$ search that exploits the Higgs boson decay to a pair of photons. For narrow isospin singlet T$'$ states with masses up to 1.1 TeV, the excellent diphoton invariant mass resolution of 1-2% results in an increased sensitivity compared to previous searches based on the same production mechanism. The electroweak production of a T$'$ quark with mass up to 960 GeV is excluded at 95% confidence level, assuming a coupling strength $\kappa_\mathrm{T}$ = 0.25 and a relative decay width $\Gamma/M_{\mathrm{T}'}$ $\lt$ 5%.
The combined, leptonic plus hadronic, expected (dotted black) and observed (solid black) upper limits at 95% CL on $\sigma_{T^\prime bq} \times \mathcal{B}_{T^\prime \rightarrow tH}$ displayed as a function of $\rm{M}_{T^\prime}$. The green (yellow) band represents the 68% (95%) of the limit values expected under the background-only hypothesis. The theoretical cross sections for the singlet $T^\prime$ production with representative $\kappa_T$-values fixed at 0.1, 0.15, 0.2 and 0.25 (for $\Gamma/\rm{M}_{T^\prime} < 5\%$) are shown as solid red lines. The theoretical cross sections for the singlet $T^\prime$ production with $\Gamma/\rm{M}_{T^\prime}$ = 1 and 5% are also shown in table.
The combined, leptonic plus hadronic, expected (dotted black) and observed (solid black) upper limits at 95% CL on the $T^\prime$ coupling to third-generation quarks, $\kappa_{T}$, under the narrow width approximation (NWA) displayed as a function of $\rm{M}_{T^\prime}$. The green (yellow) band represents the 68% (95%) of the limit values expected under the background-only hypothesis. The theoretical $\kappa_{T}$ values corresponding to the $\Gamma/\rm{M}_{T^\prime}$-values fixed at 1, 2, 3, 4, and 5% are shown as red dashed lines.
The expected (dotted black) and observed (solid black) upper limits at 95% CL on $\sigma_{T^\prime bq(T^\prime \rightarrow tH)}$ in the leptonic channel displayed as a function of $\rm{M}_{T^\prime}$. The green (yellow) band represents the 68% (95%) of the limit values expected under the background-only hypothesis. The theoretical cross sections for the singlet $T^\prime$ production with representative $\kappa_T$-values fixed at 0.1, 0.15, 0.2 and 0.25 (for $\Gamma/\rm{M}_{T^\prime} < 5\%$) are shown as solid red lines.
The mass of the top quark is measured in 36.3 fb$^{-1}$ of LHC proton-proton collision data collected with the CMS detector at $\sqrt{s}$ = 13 TeV. The measurement uses a sample of top quark pair candidate events containing one isolated electron or muon and at least four jets in the final state. For each event, the mass is reconstructed from a kinematic fit of the decay products to a top quark pair hypothesis. A profile likelihood method is applied using up to four observables to extract the top quark mass. The top quark mass is measured to be 171.77 $\pm$ 0.37 GeV. This approach significantly improves the precision over previous measurements.
Fit values for the top quark mass value and the nuisance parameters corresponding to the different uncertainty sources. All nuisance parameters have a prefit uncertainty of 1.
Covariance matrix for the top quark mass value and the nuisance parameters corresponding to the different uncertainty sources. All nuisance parameters have a prefit uncertainty of 1. The (statistical) uncertainty in mTop in the matrix includes the contributions from limited simulation sample sizes.
For the first time at LHC energies, the forward rapidity gap spectra from proton-lead collisions for both proton and lead dissociation processes are presented. The analysis is performed over 10.4 units of pseudorapidity at a center-of-mass energy per nucleon pair of $\sqrt{s_\mathrm{NN}}$ = 8.16 TeV, almost 300 times higher than in previous measurements of diffractive production in proton-nucleus collisions. For lead dissociation processes, which correspond to the pomeron-lead event topology, the EPOS-LHC generator predictions are a factor of two below the data, but the model gives a reasonable description of the rapidity gap spectrum shape. For the pomeron-proton topology, the EPOS-LHC, QGSJET II, and HIJING predictions are all at least a factor of five lower than the data. The latter effect might be explained by a significant contribution of ultra-peripheral photoproduction events mimicking the signature of diffractive processes. These data may be of significant help in understanding the high energy limit of quantum chromodynamics and for modeling cosmic ray air showers.
Differential cross section for events with Pomeron-Lead ($\mathrm{I\!P}\mathrm{Pb}$) topology obtained at the reconstruction level for $|\eta| < 3$ region. Forward Rapidity Gap definition: $|\eta| < 2.5$: $p_{T}^{track} < 200$ MeV and $\sum \limits_{bin} E^{PF} < 6$ GeV $|\eta| \in [2.5,3.0]$: $\sum \limits_{bin} E_{neutral}^{PF} < 13.4$ GeV
Differential cross section for events with Pomeron-Proton ($\mathrm{I\!P}\mathrm{p} + \gamma \mathrm{p}$) topology obtained at the reconstruction level for $|\eta| < 3$ region. Forward Rapidity Gap definition: $|\eta| < 2.5$: $p_{T}^{track} < 200$ MeV and $\sum \limits_{bin} E^{PF} < 6$ GeV $|\eta| \in [2.5,3.0]$: $\sum \limits_{bin} E_{neutral}^{PF} < 13.4$ GeV
Reconstruction level differential cross section spectla, obtained for the central acceptance, $|\eta| < 3$, for events with Pomeron-Lead ($\mathrm{I\!P}\mathrm{Pb}$) topology compared to the to the EPOS-LHC predictions, broken down into the non-diffractive (ND), central diffractive (CD), single diffractive (SD) and double diffractive (DD) components. Forward Rapidity Gap definition: $|\eta| < 2.5$: $p_{T}^{track} < 200$ MeV and $\sum \limits_{bin} E^{PF} < 6$ GeV $|\eta| \in [2.5,3.0]$: $\sum \limits_{bin} E_{neutral}^{PF} < 13.4$ GeV
A search for physics beyond the standard model (SM) in final states with an electron or muon and missing transverse momentum is presented. The analysis uses data from proton-proton collisions at a centre-of-mass energy of 13 TeV, collected with the CMS detector at the LHC in 2016–2018 and corresponding to an integrated luminosity of 138 fb−1. No significant deviation from the SM prediction is observed. Model-independent limits are set on the production cross section of W’ bosons decaying into lepton-plus-neutrino final states. Within the framework of the sequential standard model, with the combined results from the electron and muon decay channels a W’ boson with mass less than 5.7 TeV is excluded at 95% confidence level. Results on a SM precision test, the determination of the oblique electroweak W parameter, are presented using LHC data for the first time. These results together with those from the direct W’ resonance search are used to extend existing constraints on composite Higgs scenarios. This is the first experimental exclusion on compositeness parameters using results from LHC data other than Higgs boson measurements.
Product of signal selection efficiency and acceptance as a function of resonance mass for a SSM WPRIME decaying to electron or muon plus neutrino.It is calculated as the number of WPRIME signal events passing the selection process over the number of generated events. In the selection process there is no requirement on a minimum $M_T$ applied. The SSM WPRIME signal samples have been generated with PYTHIA 8.2. More details in paper
Observed and expected number of events in the electron and muon channels, collected during three years (2016, 2017, and 2018), for selected values of $M_T$ thresholds. The statistical and systematic uncertainties are added in quadrature providing the total uncertainty.
Observed and expected-from-SM number of events in the electron and muon channels, collected during three years (2016, 2017, and 2018), for two steps in the selection procedure: 1) one high-quality high-$p_T$ lepton with $p_T$ > 240(53) GeV for E(MU), and no other lepton in the event, with $M_T$ > 400(120) GeV for events with E(MU). 2) additionally the ratio of the lepton $p_T$ and $p_T^{miss}$ must be 0.4 < $p_T$/$p_T^{miss}$ < 1.5 and the azimuthal angular difference between them, ${\Delta\phi}$> 2.5. The signal yield for an SSM WPRIME of mass 5.6 TeV is also included.
A measurement is presented for the electroweak production of a W boson, a photon ($\gamma$), and two jets (j) in proton-proton collisions. The leptonic decay of the W boson is selected by requiring one identified electron or muon and large missing transverse momentum. The two jets are required to have large invariant dijet mass and large separation in pseudorapidity. The measurement is performed with the data collected by the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb$^{-1}$. The cross section for the electroweak W$\gamma$jj production is 23.5 $^{+4.9}_{-4.7}$ fb, whereas the total cross section for W$\gamma$jj production is 113 $\pm$ 13 fb. Differential cross sections are also measured with the distributions unfolded to the particle level. All results are in agreement with the standard model expectations. Constraints are placed on anomalous quartic gauge couplings (aQGCs) in terms of dimension-8 effective field theory operators. These are the most stringent limits to date on the aQGCs parameters $f_\mathrm{M,2-5}$$/$$\Lambda^4$ and $f_\mathrm{T,6-7}$$/$$\Lambda^4$.
The 2D distributions used in the fit for the total EW W$\gamma$ cross section measurement. The hatched bands represent the systematic uncertainties in the predicted yields. The expectation is shown after the fit to the data and overflow bin has been considered.
The 2D distributions used in the fit for the total EW W$\gamma$ cross section measurement. The hatched bands represent the systematic uncertainties in the predicted yields. The expectation is shown after the fit to the data and overflow bin has been considered.
Differential cross sections for the EW W$\gamma$jj production. Given that the ranges of some variables extend to infinity, the last bins accommodate all the events up to infinity as marked by the bin label.
A search for physics beyond the standard model (SM) in the final state with a hadronically decaying tau lepton and a neutrino is presented. This analysis is based on data recorded by the CMS experiment from proton-proton collisions at a center-of-mass energy of 13 TeV at the LHC, corresponding to a total integrated luminosity of 138 fb$^{=1}$. The transverse mass spectrum is analyzed for the presence of new physics. No significant deviation from the SM prediction is observed. Limits are set on the production cross section of a W' boson decaying into a tau lepton and a neutrino. Lower limits are set on the mass of the sequential SM-like heavy charged vector boson and the mass of a quantum black hole. Upper limits are placed on the couplings of a new boson to the SM fermions. Constraints are put on a nonuniversal gauge interaction model and an effective field theory model. For the first time, upper limits on the cross section of $t$-channel leptoquark (LQ) exchange are presented. These limits are translated into exclusion limits on the LQ mass and on its coupling in the $t$-channel. The sensitivity of this analysis extends into the parameter space of LQ models that attempt to explain the anomalies observed in B meson decays. The limits presented for the various interpretations are the most stringent to date. Additionally, a model-independent limit is provided.
The transverse mass distribution of $ au$ leptons and missing transverse momentum observed in the Run-2 data (black dots with statistical uncertainty) as well as the expectation from SM processes (stacked histograms). Different signal hypotheses normalized to 10 fb$^{-1}$ are illustrated as dashed lines for exemplary SSM W$\prime$ boson, QBH and EFT signal hypotheses. The ratios of the background-subtracted data yields to the expected background yields are presented in the lower panel. The combined statistical and systematic uncertainties in the background are represented by the grey shaded band in the ratio panel.
Bayesian upper exclusion limits at 95% CL on the product of the cross section and branching fraction of a W$\prime$ boson decaying to a $\tau$ lepton and a neutrino in the SSM model. For this model, W$\prime$ boson masses of up to 4.8 TeV can be excluded. The limit is given by the intersection of the observed (solid) limit and the theoretical cross section (blue dotted curve). The 68 and 95% quantiles of the limits are represented by the green and yellow bands, respectively. The $\sigma \mathcal{B}$ for an SSM W' boson, along with its associated uncertainty, calculated at NNLO precision in QCD is shown.
Bayesian 95% CL model-independent upper limit on the product of signal cross sections and branching fraction for the $\tau+\nu$ decay for a back-to-back $\tau$ lepton plus $p_{T}^{miss}$ topology. To calculate this limit, all events for signal, background, and data are summed starting from a minimum $m_{T}$ threshold and then divided by the total number of events. No assumption on signal shape is included in this limit. The expected (dashed line) and observed (solid line) limits are shown as well as the 68% and 95% CL uncertainty bands (green and yellow, respectively).
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