A search is performed for a new resonance X decaying into either a pair of Higgs bosons (HH) or into a Higgs boson and a new scalar boson Y (HY), using proton-proton collision data collected at $\sqrt{s}$ = 13 TeV, corresponding to an integrated luminosity of 138 fb$^{-1}$. This study performs a comprehensive exploitation of the bbZZ events, encompassing the following decay topologies. One H candidate is identified through its decay into a bottom quark-antiquark pair, while the other H or the Y candidate is selected through its decay into a pair of Z bosons. One Z boson is required to decay leptonically and the other, to decay into a pair of quarks or neutrinos. Events of interest are categorized based on the Lorentz boosts of the hadronically decaying H and Z bosons. Machine-learning-based discriminants, together with the reconstructed resonance mass, are employed across the different categories to separate signal from backgrounds, and their corresponding distributions are included in a simultaneous fit. No significant deviations from the standard model predictions are observed. Upper limits at the 95% confidence level are set on the HH and HY production cross sections. For resonant HH production, the upper limit on the cross section of pp $\to$ HH production is 1 pb for a high-mass resonance. For HY production, the upper limit on the cross section of the process pp $\to$ X $\to$ bbZZ is approximately 5 fb for a high-mass resonance. This is comparable to the sensitivity achieved in other analyses, which focus on H decays to $γγ$ or $ττ$ and Y decays into a pair of bottom quarks or massive vector bosons.
Pre-fit distributions of $\Delta R(\ell,\ell)$ in the SR qq0M, combining the electron and muon channel and using all three data-taking years. The hatched bands represent the total systematic uncertainties in the backgrounds. The last bin includes overflow.
Pre-fit distributions of HT in the SR qq0M, combining the electron and muon channel and using all three data-taking years. The hatched bands represent the total systematic uncertainties in the backgrounds. The last bin includes overflow.
Pre-fit distributions of $\Delta R(\ell_1,b_1)$ in the SR qq0M, combining the electron and muon channel and using all three data-taking years. The hatched bands represent the total systematic uncertainties in the backgrounds. The last bin includes overflow.
Event shape variables, constructed from the four-momenta of the final-state objects in an event, are sensitive to the predictions of quantum chromodynamics in multijet production. A measurement of five event shape variables is presented, using proton-proton collision data collected at a centre-of-mass energy of 13 TeV with the CMS detector during 2016$-$2018, corresponding to an integrated luminosity of 138 fb$^{-1}$. The variables are evaluated using the charged particles inside jets. After correcting for detector effects, their distributions are compared with the results from the predictions from a number of models for multijet production. Overall, there is general agreement between several theoretical predictions and the data.
Normalized unfolded distributions of Complement of transverse thrust($\tau_{\perp}$) for $83<H_{T,2}<109$ GeV
Normalized unfolded distributions of Complement of transverse thrust($\tau_{\perp}$) for $109<H_{T,2}<176$ GeV
Normalized unfolded distributions of Complement of transverse thrust($\tau_{\perp}$) for $176<H_{T,2}<247$ GeV
Production fraction ratios of B$^+$, B$^0$, and B$^0_\mathrm{s}$ mesons are measured in proton-proton collisions at $\sqrt{s}$ = 13 TeV using a special data set recorded in 2018 with high-rate triggers designed to collect an unbiased sample of $10^{10}$ b hadrons with the CMS experiment at the LHC. These data allow the use of the open-charm decays of B mesons (B$_\mathrm{(s)}$$\to$$π$D$_\mathrm{(s)}$) where the D meson decays into fully hadronic final states. Production fraction ratios as functions of B meson transverse momentum ($p_\mathrm{T}$) and rapidity ($y$) are measured using the open-charm decays in the kinematic range of 8 $\lt$$p_\mathrm{T}$$\lt$ 60 GeV and $\lvert y \rvert$$\lt$ 2.25. In addition, the same data are used to measure the relative production fraction ratios with the charmonium decay channels (B$_\mathrm{(s)}$$\to$ X$\,$J/$ψ$ with X indicating a K$^+$, K$^*$(892)$^0$, or $ϕ$(1020) meson) with the J/$ψ$ meson decaying into a pair of muons. By utilizing known branching fractions, precision theoretical calculations, and the open-charm results, the production fraction ratios in the charmonium samples are determined with an absolute normalization for the first time. These results also improve several world-average values of the ratios of branching fractions of B meson decays to charmonium and open-charm states. Finally, we test isospin invariance in B meson production in proton-proton collisions and observe that it holds within the experimental precision.
The invariant mass distribution of $B^+$ candidates, corrected using the $D^0$ meson mass, is shown for $13 < p_{T} < 18$ GeV along with the corresponding fit.
The invariant mass distribution of $B^0$ candidates, corrected using the $D^-$ meson mass, is shown for $18 < p_{T} < 23$ GeV along with the corresponding fit.
The invariant mass distribution of $B_s^{0}$ candidates, corrected using the $D^-_{s}$ meson mass, is shown for $23 < p_{T} < 28$ GeV along with the corresponding fit.
Three structures, X(6600), X(6900), and X(7100), have emerged from the J$/ψ\,$J$/ψ$ (J$/ψ$\to$μ^+μ^-$) mass spectrum. These are candidates of all-charm tetraquarks, an exotic form of hadronic matter. A clearer picture of these states is obtained using proton-proton collision data collected by the CMS detector that corresponds to 315 fb$^{-1}$, which yields 3.6 times more J$/ψ\,$J$/ψ$ pairs than previous studies by CMS. All three structures, and their mutual interference, have statistical significances above five standard deviations. The presence of interference implies that the structures have common quantum numbers. Their squared masses align linearly with a resonance index and have natural widths that systematically decrease as the index increases. These features are consistent with radial excitations of tetraquarks composed of two aligned spin-1 diquarks without orbital excitation, and disfavor other interpretations. The J$/ψ\,$$ψ$(2S) $\to$$μ^+μ^-μ^+μ^-$ decay mode is also explored and the X(6900) and X(7100) states are found with significances exceeding 8 and 4 standard deviations, respectively.
Measured masses and widths of the three X states from the fits to the $\mathrm{J}/\psi\mathrm{J}/\psi$ mass spectrum from the Run 2+3 data sets. The amplitudes (phases) of the X(6600) and X(7100) relative to the X(6900) state are r1 = 1.790 ± 0.737 (phi1 = 1.693 ± 0.660 rad) and r3 = 0.429 ± 0.267 (phi3 = -0.388 ± 0.410 rad), respectively.
Measured masses and widths of the three X states from the fits to the $\mathrm{J}/\psi \psi(2S)$ mass spectrum from the Run 2+3 data sets.The amplitudes (phases) of the X(7100) relative to the X(6900) state are r = 0.692 ± 0.225 (phi1 = -1.486 ± 0.970 rad).
The $\mathrm{J}/\psi\mathrm{J}/\psi$ invariant-mass spectrum covering the full range of the fit: 6.175 - 15.0 GeV.
The observation of associated production of an $Υ$(1S) meson with a Z boson and a measurement of the ratio of its fiducial cross section to the fiducial cross section of the Z boson are presented. Both the $Υ$(1S) meson and the Z boson are identified via decays into a pair of opposite-sign muons. The analysis is based on proton-proton (pp) collision data at $\sqrt{s}$ = 13 TeV, collected with the CMS detector in 2016$-$2018 and corresponding to an integrated luminosity of 138 fb$^{-1}$. Using the production of the Z boson decaying into four muons as a normalization channel, the ratio of the fiducial cross sections $σ$(pp $\to$ Z $+$$Υ$(1S))$\mathcal{B}$(Z $\to$$μ^+μ^-$)$\mathcal{B}$($Υ$(1S) $\to$$μ^+μ^-$ ) to $σ$(pp $\to$ Z)$\mathcal{B}$(Z $\to$ 4$μ$) is measured to be $\mathcal{R}_{\mathrm{Z+Υ}\mathrm{(1S)}}$ = (21.1 $\pm$ 55 (stat) $\pm$ 0.6 (syst) $\times$ 10$^{-3}$), where stat and syst denote the statistical and systematic uncertainties, respectively. The result is used to extract the effective double-parton scattering cross section $σ_\text{eff}$ = 13.0$^{+7.7}_{-3.4}$. In addition, for the first time, $σ_\text{eff}$ is measured in bins of the transverse momentum of the $Υ$(1S) meson or of the Z boson.
$\sigma(\mathrm{pp}\to\mathrm{Z+Y(1S)})\mathcal{B}(\mathrm{Z}\to\mu\mu)\mathcal{B}(\mathrm{Y(1S)}\to\mu\mu) / \sigma(\mathrm{pp}\to\mathrm{Z})\mathcal{B}(\mathrm{Z}\to\mu\mu\mu\mu)$
DPS $\sigma(\mathrm{pp}\to\mathrm{Z+Y(1S)})\mathcal{B}(\mathrm{Z}\to\mu\mu)\mathcal{B}(\mathrm{Y(1S)}\to\mu\mu) / \sigma(\mathrm{pp}\to\mathrm{Z})\mathcal{B}(\mathrm{Z}\to\mu\mu\mu\mu)$
$\sigma(\mathrm{pp}\to\mathrm{Z+Y(1S)})\mathcal{B}(\mathrm{Z}\to\mu\mu)\mathcal{B}(\mathrm{Y(1S)}\to\mu\mu) / \sigma(\mathrm{pp}\to\mathrm{Z})\mathcal{B}(\mathrm{Z}\to\mu\mu\mu\mu)$
A search is performed for a heavy scalar resonance X decaying to a Higgs boson (H) and a Higgs-like scalar boson (Y) in the two bottom quark (H $\to$$\mathrm{b\bar{b}}$) and four quark (Y $\to$ VV $\to$ 4q) final state, where V denotes a W or Z boson. Masses of the X between 900 and 4000 GeV and the Y between 60 and 2800 GeV are considered. The search is performed in data collected by the CMS experiment at the CERN LHC from proton-proton collisions at 13 TeV center-of-mass energy, with a data set corresponding to a total integrated luminosity of 138 fb$^{-1}$. It targets the Lorentz-boosted regime, in which the products of the H $\to$$\mathrm{b\bar{b}}$ decay can be reconstructed as a single large-area jet, and those from the Y $\to$ VV $\to$ 4q decay as either one Y $\to$ 4q or two V to $\mathrm{q\bar{q}}$ jets. Jet identification and mass reconstruction exploit machine-learning tools, including a novel attention-based "particle transformer" for Y $\to$ 4q identification. No significant excess is observed in the data above the standard model background expectation. Upper limits on the product of production cross section and branching fraction as low as 0.2 fb are derived at 95% confidence level for various mass hypotheses. This is the first search at the LHC for scalar resonances in the all-hadronic $\mathrm{b\bar{b}}$VV decay channel.
Projected distributions of the $\mathrm{m}_{\mathrm{X}}^{\text{rec}}$ observable in the SP region of the fully merged (FM) category, after a maximum likelihood fit to the data with an $\mathrm{X} \to \mathrm{HY} \to \mathrm{b}\bar{\mathrm{b}}\mathrm{WW}$ signal with $\mathrm{m}_{\mathrm{X}} = 900$ GeV and $\mathrm{m}_{\mathrm{Y}} = 80$ GeV and best-fit production cross section times branching fraction of 15 fb. The lower panels show the pull per bin, defined as $(\mathrm{data} - \mathrm{bkg.})/\sigma_{\mathrm{stat}}$, where $\sigma_{\mathrm{stat}}$ is the statistical uncertainty in the data, as well as the systematic uncertainty normalized to $\sigma_{\mathrm{stat}}$. The full yields in each bin are presented here without division by the bin width as shown in the paper.
Projected distributions of the $\mathrm{m}_{\mathrm{Y}}^{\text{rec}}$ observable in the SP region of the fully merged (FM) category, after a maximum likelihood fit to the data with an $\mathrm{X} \to \mathrm{HY} \to \mathrm{b}\bar{\mathrm{b}}\mathrm{WW}$ signal with $\mathrm{m}_{\mathrm{X}} = 900$ GeV and $\mathrm{m}_{\mathrm{Y}} = 80$ GeV and best-fit production cross section times branching fraction of 15 fb. The lower panels show the pull per bin, defined as $(\mathrm{data} - \mathrm{bkg.})/\sigma_{\mathrm{stat}}$, where $\sigma_{\mathrm{stat}}$ is the statistical uncertainty in the data, as well as the systematic uncertainty normalized to $\sigma_{\mathrm{stat}}$. The full yields in each bin are presented here without division by the bin width as shown in the paper.
Projected distributions of the $\mathrm{m}_{\mathrm{X}}^{\text{rec}}$ observable in the SP region of the semimerged (SM) category, after a maximum likelihood fit to the data with an $\mathrm{X} \to \mathrm{HY} \to \mathrm{b}\bar{\mathrm{b}}\mathrm{WW}$ signal with $\mathrm{m}_{\mathrm{X}} = 1200$ GeV and $\mathrm{m}_{\mathrm{Y}} = 900$ GeV and best-fit production cross section times branching fraction of 250 fb. The lower panels show the pull per bin, defined as $(\mathrm{data} - \mathrm{bkg.})/\sigma_{\mathrm{stat}}$, where $\sigma_{\mathrm{stat}}$ is the statistical uncertainty in the data, as well as the systematic uncertainty normalized to $\sigma_{\mathrm{stat}}$. The full yields in each bin are presented here without division by the bin width as shown in the paper.
This analysis presents an observation of the photon-fusion production of W boson pairs using the CMS detector at the LHC. The total cross section of the W$^+$W$^-$ production in photon fusion is measured using proton-proton collision data with an integrated luminosity of 138 fb$^{-1}$ collected with the CMS detector in 2016$-$2018 at a center-of-mass energy of $\sqrt{s}$ = 13 TeV. Events are selected in the final state with one isolated electron and one isolated muon, and no additional tracks associated with the electron-muon production vertex. The total and fiducial production cross sections are 643$^{+82}_{-78}$ fb and 3.96$^{+0.53}_{-0.51}$ fb, respectively, in agreement with the standard model predictions of 631 $\pm$ 126 fb and 3.87 $\pm$ 0.77 fb. This agreement enables stringent constraints to be imposed on anomalous quartic gauge couplings within a dimension-8 effective field theory framework.
Normalized simulated $N_{tracks}$ distributions for signal and background processes.
Normalized simulated acoplanarity distributions for signal and background processes. The acoplanarity distribution is shown for events with $N_{tracks}=0$.
Observed and predicted $p_{T}^{e\mu}$ distributions for events with $N_{tracks}=0$, using 2016--2018 data. The distributions are shown after the maximum likelihood fit to the data ('postfit distributions'). The observed data and their associated Poissonian statistical uncertainty are shown with black markers with vertical error bars. The uncertainty band accouts for all sources of background and signal uncertainty, systematic as well as statistical, after the fit. The last bin includes the overflow. The lower panels show the ratio of data to sum of signal and background contributions, before (prefit, open red circles) and after (black full markers) the maximum likelihood fit.
The production cross sections of the $Υ$(1S), $Υ$(2S), and $Υ$(3S) mesons are measured in proton-proton collisions at $\sqrt{s}$ = 13.6 TeV, using a data sample collected in 2022 by the CMS experiment and corresponding to an integrated luminosity of 37.4 fb$^{-1}$. The measurement is performed in the $μ^+μ^-$ decay channels, differentially as a function of transverse momentum in the 20$-$200 GeV range, in the $\lvert y\rvert$$\lt$ 0.6 and 0.6 $\lt$$\lvert y\rvert$$\lt$ 1.2 rapidity intervals.
Differential cross section times branching fraction for Upsilon(1S) -> mu+ mu-, measured in the rapidity range |y| < 0.6. This table corresponds to Figure 2 (left panel for |y|<0.6, right panel for 0.6<|y|<1.2) and Table A.1 in the paper. Results assume unpolarized production; polarization correction factors are provided in Table 6.
Differential cross section times branching fraction for Upsilon(1S) -> mu+ mu-, measured in the rapidity range 0.6 < |y| < 1.2. This table corresponds to Figure 2 (left panel for |y|<0.6, right panel for 0.6<|y|<1.2) and Table A.1 in the paper. Results assume unpolarized production; polarization correction factors are provided in Table 6.
Differential cross section times branching fraction for Upsilon(2S) -> mu+ mu-, measured in the rapidity range |y| < 0.6. This table corresponds to Figure 2 (left panel for |y|<0.6, right panel for 0.6<|y|<1.2) and Table A.2 in the paper. Results assume unpolarized production; polarization correction factors are provided in Table 6.
In the physics program of the CMS experiment during the CERN LHC Run 3, which started in 2022, the long-lived particle triggers have been improved and extended to expand the scope of the corresponding searches. These dedicated triggers and their performance are described in this paper, using several theoretical benchmark models that extend the standard model of particle physics. The results are based on proton-proton collision data collected with the CMS detector during 2022$-$2024 at a center-of-mass energy of 13.6 TeV, corresponding to integrated luminosities of up to 123 fb$^{-1}$.
Offline standard tracking efficiency during Run~3 for different tracking iterations, as a function of simulated radial position of the track production vertex. In the figure, $t\bar{t}$ simulation for 2025 conditions and an average PU of 62 is used, and the tracks are required to have $\mathrm{p_T}>0.9$ GeV and $|\eta|<2.5$. The tracking efficiency is defined as the ratio of the simulated tracks (with the aforementioned selection requirements) geometrically matched to a reconstructed track, divided by the total simulated tracks passing the selections.
Overall standard tracking efficiency at the HLT during Run~3, as a function of the simulated radial position of the track production vertex. In the figure, $t\bar{t}$ simulation for 2025 conditions and an average PU of 62 is used, and the tracks are required to have $\mathrm{p_T}>0.9$ GeV and $|\eta|<2.5$. The tracking efficiency is defined as the ratio of the simulated tracks (with the aforementioned selection requirements) geometrically matched to a reconstructed track, divided by the total simulated tracks passing the selections.
L1T+HLT efficiency of the MET+IsoTrk trigger as a function of the number of tracker layers with valid measurements of the track that pass the offline requirements, in $\tilde{\chi}_{1}^{\pm} \rightarrow \tilde{\chi}_{1}^{0}$+X simulated events for 2022 conditions, where $m_{\tilde{\chi}_{1}^{\pm}}=900$ GeV and $\tilde{\chi}_{1}^{0}$ is nearly mass-degenerate with $\tilde{\chi}_{1}^{\pm}$. The efficiency is shown for LLPs with $c\tau=$ 10, 100, and 1000 cm in black, blue, and red, respectively.
Gauge-mediated supersymmetry-breaking models provide a strong motivation to search for a supersymmetric partner of the tau lepton (stau) with a macroscopic lifetime. Long-lived stau decays produce tau leptons that are displaced from the primary proton-proton interaction vertex, leading to an unconventional signature. This paper presents a search for the direct production of long-lived staus decaying within the CMS tracker volume in proton-proton collisions at $\sqrt{s}$ = 13 TeV, performed for the first time with an identification algorithm based on a graph neural network dedicated to displaced tau leptons. The data sample, corresponding to an integrated luminosity of 138 fb$^{-1}$, was recorded with the CMS experiment at the CERN LHC between 2016 and 2018. This search excludes, at 95% confidence level, stau masses, $m_\tildeτ$, in the 126$-$260 (906$-$425) GeV range for a proper decay length of 50 mm in the maximally mixed (mass-degenerate) scenario, while for $m_\tildeτ $ = 200 GeV, stau proper decay lengths are excluded in the range 21$-$94 (6$-$333) mm. These results improve the exclusion limits compared to previous searches, and extend the parameter space explored in the context of supersymmetry.
Distributions of $p_\text{T, j2}$ for data and the predicted background, in the signal region. The signal distributions expected in the maximally mixed scenario for a few representative sets of $(m_{\tilde{\tau}} [\text{GeV}], c\tau_{0} [\text{mm}])$ values are overlaid: (100, 10), (100, 50), (100, 100), (200, 10), (200, 50), (200, 100), (300, 10), (300, 50), and (300, 100). In bins where the observed yield is zero, the Garwood interval at 68% CL is shown as a positive uncertainty. The last bin includes the overflow.
Distributions of $p^\text{miss}_\text{T}$ for data and the predicted background, in the signal region. The signal distributions expected in the maximally mixed scenario for a few representative sets of $(m_{\tilde{\tau}} [\text{GeV}], c\tau_{0} [\text{mm}])$ values are overlaid: (100, 10), (100, 50), (100, 100), (200, 10), (200, 50), (200, 100), (300, 10), (300, 50), and (300, 100). In bins where the observed yield is zero, the Garwood interval at 68% CL is shown as a positive uncertainty. The last bin includes the overflow.
Distributions of $m_\text{T2}$ for data and the predicted background, in the signal region. The signal distributions expected in the maximally mixed scenario for a few representative sets of $(m_{\tilde{\tau}} [\text{GeV}], c\tau_{0} [\text{mm}])$ values are overlaid: (100, 10), (100, 50), (100, 100), (200, 10), (200, 50), (200, 100), (300, 10), (300, 50), and (300, 100). In bins where the observed yield is zero, the Garwood interval at 68% CL is shown as a positive uncertainty. The last bin includes the overflow.