A combined statistical analysis of searches for heavy vector boson resonances decaying into pairs of W, Z, or Higgs bosons, as well as into quark pairs ($\mathrm{q\bar{q}}$, $\mathrm{b\bar{b}}$, $\mathrm{t\bar{t}}$, $\mathrm{t\bar{b}}$) or lepton pairs ($\ell^+\ell^-$, $\ell\barν$), with $\ell =$ e, $μ$, $τ$, is presented. The results are based on proton-proton collision data at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb$^{-1}$, collected by the CMS experiment from 2016 to 2018. No significant deviation from the expectations of the standard model is observed. The results are interpreted in the simplified heavy vector triplet (HVT) framework, setting 95% confidence level upper limits on the production cross sections and coupling strengths to standard model particles or the HVT bosons. The results exclude HVT resonances with masses below 5.5 TeV in a weakly coupled scenario, below 4.8 TeV in a strongly coupled scenario, and up to 2.0 TeV in the case of production via vector boson fusion. The combination provides the most stringent constraints to date on new phenomena predicted by the HVT model.
Expected and observed 95% CL upper limits on the V'boson production cross section as functions of the resonance mass mV' shown separately for the V' → quarks category. The limits are evaluated in the HVT model A scenario.
Expected and observed 95% CL upper limits on the V'boson production cross section as functions of the resonance mass mV' shown separately for the V' → leptons category. The limits are evaluated in the HVT model A scenario.
Expected and observed 95% CL upper limits on the V' boson production cross section as functions of the resonance mass mV' shown separately for the V' → bosons category. The limits are evaluated in the HVT model B scenario.
A search is presented for charged Higgs bosons (H$^\pm$) in proton-proton (pp) collision events via the pp $\to$ (b)H$^\pm$ processes, with H$^\pm$ decaying into top (t) and bottom (b) quarks. The search targets final states with one lepton, missing transverse momentum, and two or more b jets. The analysis is based on data collected at a center-of-mass energy of 13 TeV with the CMS detector at the LHC, corresponding to an integrated luminosity of 138 fb$^{-1}$. We search for charged Higgs bosons in the 200 GeV to 1 TeV mass range. The results are interpreted within the generalized two-Higgs-doublet model (g2HDM). This model predicts additional Yukawa couplings of the Higgs bosons to the top quark $ρ_\mathrm{tt}$, the top and charm quark $ρ_\mathrm{tc}$, and the top and up quark $ρ_\mathrm{tu}$. This search focuses on the real components of $ρ_\mathrm{tt}$ and $ρ_\mathrm{tc}$, which are probed up to values of unity. An excess is observed with respect to the standard model expectation with a local significance of 2.4 standard deviations for a signal with an H$^\pm$ boson mass ($m_{\mathrm{H}^\pm}$) of 600 GeV. Limits are derived on the product of the cross section $σ$(pp $\to$ (b)H$^\pm$) and branching fraction $\mathcal{B}$(H$^\pm$$\to$ tb, t $\to$ b$\ellν$), where $\ell$ = e, $μ$. The values of $ρ_\mathrm{tc} \gtrsim$ 0.15$-$0.5 are excluded at 95% confidence level, depending on the $m_{\mathrm{H}^\pm}$ and $ρ_\mathrm{tt}$ assumptions. The results represent the first search for charged Higgs bosons within the g2HDM framework and complement the existing results on additional neutral Higgs bosons.
The postfit pDNN distributions in the SR e 2b2j assuming $m_{H^\pm} = 600$ GeV. Postfit signal for $m_{H^\pm} = 600$ GeV is also shown. Beneath plot the ratio of data to predictions is shown.
The postfit pDNN distributions in the SR $\mu$ 2b2j assuming $m_{H^\pm} = 600$ GeV. Postfit signal for $m_{H^\pm} = 600$ GeV is also shown. Beneath plot the ratio of data to predictions is shown.
The postfit pDNN distributions in the SR e 3b3j assuming $m_{H^\pm} = 600$ GeV. Postfit signal for $m_{H^\pm} = 600$ GeV is also shown. Beneath plot the ratio of data to predictions is shown.
Measurements of the spin correlation coefficients in the beam basis are presented for top quark-antiquark ($\mathrm{t\bar{t}}$) systems produced in proton-proton collisions at $\sqrt{s}$ = 13 TeV collected by the CMS experiment in 2016$-$2018, and corresponding to an integrated luminosity of 138 fb$^{-1}$. The $\mathrm{t\bar{t}}$ system is reconstructed from final states containing an electron or muon, and jets. Together with the previously reported results in the helicity basis, these measurements are used to decompose the system into the Bell and spin eigenstates in various kinematic regions. The spin correlation coefficients are also used to evaluate properties of the $\mathrm{t\bar{t}}$ quantum state, such as the purity, von Neumann entropy, and entanglement. All results are consistent with standard model predictions.
Measured spin correlation coefficients in beam basis for $m(t\bar{t})$ vs. $|cos(\theta)|$ bins
Covariance for spin correlation coefficients in beam basis for $m(t\bar{t})$ vs. $|cos(\theta)|$ bins
Measured spin correlation coefficients in beam basis for $p_{T}(t)$ vs. $|cos(\theta)|$ bins
A hot and dense state of nuclear matter, known as the quark-gluon plasma, is created in collisions of ultrarelativistic heavy nuclei. Highly energetic quarks and gluons, collectively referred to as partons, lose energy as they travel through this matter, leading to suppressed production of particles with large transverse momenta ($p_\mathrm{T}$). Conversely, high-$p_\mathrm{T}$ particle suppression has not been seen in proton-lead collisions, raising questions regarding the minimum system size required to observe parton energy loss. Oxygen-oxygen (OO) collisions examine a region of effective system size that lies between these two extreme cases. The CMS detector at the CERN LHC has been used to quantify charged-particle production in inclusive OO collisions for the first time via measurements of the nuclear modification factor ($R_\mathrm{AA}$). The $R_\mathrm{AA}$ is derived by comparing particle production to expectations based on proton-proton (pp) data and has a value of unity in the absence of nuclear effects. The data for OO and pp collisions at a nucleon-nucleon center-of-mass energy $\sqrt{s_\mathrm{NN}}$ = 5.36 TeV correspond to integrated luminosities of 6.1 nb$^{-1}$ and 1.02 pb$^{-1}$, respectively. The $R_\mathrm{AA}$ is below unity with a minimum of 0.69 $\pm$ 0.04 around $p_\mathrm{T}$ = 6 GeV. The data exhibit better agreement with theoretical models incorporating parton energy loss as compared to baseline models without energy loss.
Inclusive charged particle spectra for pp collisions at 5.36 TeV for $3 < p_{T} (GeV) <103.6$. The errors represent statistical, systematics and normalization uncertainties.
Inclusive charged particle spectra for OO collisions at 5.36 TeV for $3 < p_{T} (GeV) <103.6$. The errors represent statistical, systematics and normalization uncertainties.
Inclusive charged particle R_{AA} for 5.36 TeV OO collisions for $3 < p_{T} (GeV) <103.6$. The errors represent statistical, systematics and normalization uncertainties.
The long-range collective flow of particles produced in oxygen-oxygen (OO) and neon-neon (NeNe) collisions is measured with the CMS detector at the CERN LHC. The data samples were collected at a center-of-mass energy per nucleon pair of 5.36 TeV, with integrated luminosities of 7 nb$^{-1}$ and 0.8 nb$^{-1}$ for OO and NeNe collisions, respectively. Two- and four-particle azimuthal correlations are measured over nearly five units of pseudorapidity. Significant elliptic ($v_2$) and triangular ($v_3$) flow harmonics are observed in both systems. The ratios of $v_n$ coefficients between NeNe and OO collisions reveal sensitivity to quadrupole correlations in the nuclear wave functions. Hydrodynamic models with $\textit{ab initio}$ nuclear structure inputs qualitatively reproduce the collision-overlap dependence of both the $v_n$ values and the NeNe to OO ratios. These measurements provide new constraints on hydrodynamic models for small collision systems and offer valuable input on the nuclear structure of $^{16}$O and $^{20}$Ne.
The $v_{2}\{2,\lvert\Delta\eta\rvert>2\}$, $v_{3}\{2,\lvert\Delta\eta\rvert>2\}$ and $v_{2}\{4\}$ values for charged particles as functions of centrality in OO collisions at 5.36 TeV.
The $v_{2}\{2,\lvert\Delta\eta\rvert>2\}$, $v_{3}\{2,\lvert\Delta\eta\rvert>2\}$ and $v_{2}\{4\}$ values for charged particles as functions of centrality in NeNe collisions at 5.36 TeV.
The $v_{2}\{2,\lvert\Delta\eta\rvert>2\}$ and $v_{2}\{4\}$ ratios for charged particles as functions of centrality in NeNe to OO collisions at 5.36 TeV.
A measurement of the WZ$γ$ triboson production cross section is presented. The analysis is based on a data sample of proton-proton collisions at a center-of-mass energy of $\sqrt{s}$ = 13 TeV recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 138 fb$^{-1}$. The analysis focuses on the final state with three charged leptons, $\ell^\pmν\ell^+\ell^-$, where $\ell$ = e or $μ$, accompanied by an additional photon. The observed (expected) significance of the WZ$γ$ signal is 5.4 (3.8) standard deviations. The cross section is measured in a fiducial region, where events with an $\ell$ originating from a tau lepton decay are excluded, to be 5.48 $\pm$ 1.11 fb, which is compatible with the prediction of 3.69 $\pm$ 0.24 fb at next-to-leading order in quantum chromodynamics. Exclusion limits are set on anomalous quartic gauge couplings and on the production cross sections of massive axion-like particles.
The distributions of the variables used in the simultaneous fit for the nonprompt $l$ CR. The black points with error bars represent the data and their statistical uncertainties, whereas the shaded band represents the predicted uncertainties. The bottom panel in each figure shows the ratio of the number of events observed in data to that of the total SM prediction. The last bin of each plot has been extended to include the overflow contribution.
The distributions of the variables used in the simultaneous fit for the nonprompt $\gamma$ CR. The black points with error bars represent the data and their statistical uncertainties, whereas the shaded band represents the predicted uncertainties. The bottom panel in each figure shows the ratio of the number of events observed in data to that of the total SM prediction. The last bin of each plot has been extended to include the overflow contribution.
The distributions of the variables used in the simultaneous fit for the ZZ CR. The black points with error bars represent the data and their statistical uncertainties, whereas the shaded band represents the predicted uncertainties. The bottom panel in each figure shows the ratio of the number of events observed in data to that of the total SM prediction. The last bin of each plot has been extended to include the overflow contribution.
A search for $t$-channel exchange of leptoquarks (LQs) is performed in dimuon and dielectron spectra using proton-proton collision data collected at $\sqrt{s}$ = 13 TeV with the CMS detector at the CERN LHC. The data correspond to an integrated luminosity of 138 fb$^{-1}$. Eight scenarios are considered, in which scalar or vector LQs couple up or down quarks to muons or electrons, for dilepton invariant masses above 500 GeV. The LQ masses are probed up to 5 TeV, beyond a regime probed by previous pair-production and single-production searches. The differential distributions of dilepton events are fit to templates that model the nonresonant LQ exchange and various standard model background processes. Limits are set on LQ-fermion coupling strengths for scalar and vector LQ masses in the 1-5 TeV range at 95% confidence level, establishing stringent limits on first- and second-generation LQs.
Observed and Expected UL exclusions on the $BR(H\to SUEP)$ of hadronic signals with $m_{A'} = 0.7\;GeV$ and $BR(A' \rightarrow ee) = BR(A' \rightarrow \mu\mu) = 0.15$ and $BR(A' \rightarrow \pi\pi) = 0.7$.
The observed data in the dielectron channel and the fitted signal-plus-background templates, shown for the $S_{e u}$ scenario with a candidate LQ mass of 2.5 TeV. Distributions of events are binned in the reconstructed dilepton mass, rapidity, and cosine theta.
Observed and Expected UL exclusions on the $BR(H\to S)$ of leptonic signals with $m_{A'} = 0.5\;GeV$ and $BR(A' \rightarrow ee) = BR(A' \rightarrow \mu\mu) = 0.2$ and $BR(A' \rightarrow \pi\pi) = 0.6$.
A search is presented for the resonant production of a pair of standard model-like Higgs bosons using data from proton-proton collisions at a centre-of-mass energy of 13 TeV, collected by the CMS experiment at the CERN LHC in 2016-2018, corresponding to an integrated luminosity of 138 fb$^{-1}$. The final state consists of two b quark-antiquark pairs. The search is conducted in the region of phase space where at least one of the pairs is highly Lorentz-boosted and is reconstructed as a single large-area jet. The other pair may be either similarly merged or resolved, the latter reconstructed using two b-tagged jets. The data are found to be consistent with standard model processes and are interpreted as 95% confidence level upper limits on the product of the cross sections and the branching fractions of the spin-0 radion and the spin-2 bulk graviton that arise in warped extradimensional models. The limits set are in the range 9.74-0.29 fb and 4.94-0.19 fb for a narrow radion and a graviton, respectively, with masses between 1 and 3 TeV. For a radion and for a bulk graviton with widths 10% of their masses, the limits are in the range 12.5-0.35 fb and 8.23-0.23 fb, respectively, for the same masses. These limits result in the exclusion of a narrow-width graviton with a mass below 1.2 TeV, and of narrow and 10%-width radions with masses below 2.6, and 2.9 TeV, respectively.
Slices of 2D distributions of observed events and the post-fit templates in the LL pass region, projected onto the plane of leading jet mass mJ1, including expected radion signal at 1.5 TeV.
Slices of 2D distributions of observed events and the post-fit templates in the LL pass region, projected onto the plane of leading jet mass mJ1, including expected radion signal at 1.5 TeV.
Slices of 2D distributions of observed events and the post-fit templates in the LL pass region, projected onto the plane of leading jet mass mJ1, including expected radion signal at 1.5 TeV.
Differential cross sections for top quark pair ($\mathrm{t\bar{t}}$) production are measured in proton-proton collisions at a center-of-mass energy of 13 TeV using a sample of events containing two oppositely charged leptons. The data were recorded with the CMS detector at the CERN Large Hadron Collider and correspond to an integrated luminosity of 138 fb$^{-1}$. The differential cross sections are measured as functions of kinematic observables of the $\mathrm{t\bar{t}}$ system, the top quark and antiquark and their decay products, as well as of the number of additional jets in the event. The results are presented as functions of up to three variables and are corrected to the parton and particle levels. When compared to standard model predictions based on quantum chromodynamics at different levels of accuracy, it is found that the calculations do not always describe the observed data. The deviations are found to be largest for the multi-differential cross sections.
Absolute differential ttbar production cross section measured as function of top pT at the parton level in the full phase space.
Absolute differential ttbar production cross section measured as function of top rapidity at the parton level in the full phase space.
Absolute differential ttbar production cross section measured as function of ttbar mass at the parton level in the full phase space.
A combination of fifteen top quark mass measurements performed by the ATLAS and CMS experiments at the LHC is presented. The data sets used correspond to an integrated luminosity of up to 5 and 20$^{-1}$ of proton-proton collisions at center-of-mass energies of 7 and 8 TeV, respectively. The combination includes measurements in top quark pair events that exploit both the semileptonic and hadronic decays of the top quark, and a measurement using events enriched in single top quark production via the electroweak $t$-channel. The combination accounts for the correlations between measurements and achieves an improvement in the total uncertainty of 31% relative to the most precise input measurement. The result is $m_\mathrm{t}$ = 172.52 $\pm$ 0.14 (stat) $\pm$ 0.30 (syst) GeV, with a total uncertainty of 0.33 GeV.
Uncertainties on the $m_{t}$ values extracted in the LHC, ATLAS, and CMS combinations arising from the categories described in the text, sorted in order of decreasing value of the combined LHC uncertainty.