A search for long-lived heavy neutrinos (N) in the decays of B mesons produced in proton-proton collisions at $\sqrt{s}$ = 13 TeV is presented. The data sample corresponds to an integrated luminosity of 41.6 fb$^{-1}$ collected in 2018 by the CMS experiment at the CERN LHC, using a dedicated data stream that enhances the number of recorded events containing B mesons. The search probes heavy neutrinos with masses in the range 1 $\lt$$m_\mathrm{N}$$\lt$ 3 GeV and decay lengths in the range 10$^{-2}$$\lt$$c\tau_\mathrm{N}$$\lt$ 10$^{4}$ mm, where $\tau_\mathrm{N}$ is the N proper mean lifetime. Signal events are defined by the signature B $\to$$\ell_\mathrm{B}$NX; N $\to$$\ell^{\pm} \pi^{\mp}$, where the leptons $\ell_\mathrm{B}$ and $\ell$ can be either a muon or an electron, provided that at least one of them is a muon. The hadronic recoil system, X, is treated inclusively and is not reconstructed. No significant excess of events over the standard model background is observed in any of the $\ell^{\pm} \pi^{\mp}$ invariant mass distributions. Limits at 95% confidence level on the sum of the squares of the mixing amplitudes between heavy and light neutrinos, $\vert V_\mathrm{N}\vert^2$, and on $c\tau$ are obtained in different mixing scenarios for both Majorana and Dirac-like N particles. The most stringent upper limit $\vert V_\mathrm{N}\vert^2$ $\lt$ 2.0 $\times$ 10$^{-5}$ is obtained at $m_\mathrm{N}$ = 1.95 GeV for the Majorana case where N mixes exclusively with muon neutrinos. The limits on $\vert V_\mathrm{N}\vert^2$ for masses 1 $\lt$ $m_\mathrm{N}$ $\lt$ 1.7 GeV are the most stringent from a collider experiment to date.
Expected and observed 95% CL upper limits on $|V_\mathrm{N}|^2$ as a function of $m_\mathrm{N}$ for the mixing scenario ($r_e$, $r_\mu$, $r_\tau$) = (0.0, 1.0, 0.0) and in the Majorana scenario.
Expected and observed 95% CL upper limits on $|V_\mathrm{N}|^2$ as a function of $m_\mathrm{N}$ for the mixing scenario ($r_e$, $r_\mu$, $r_\tau$) = (0.0, 0.5, 0.5) and in the Majorana scenario.
Expected and observed 95% CL upper limits on $|V_\mathrm{N}|^2$ as a function of $m_\mathrm{N}$ for the mixing scenario ($r_e$, $r_\mu$, $r_\tau$) = (0.5, 0.5, 0.0) and in the Majorana scenario.
The first search for soft unclustered energy patterns (SUEPs) is performed using an integrated luminosity of 138 fb$^{-1}$ of proton-proton collision data at $\sqrt{s}$ = 13 TeV collected in 2016-2018 by the CMS detector at the LHC. Such SUEPs are predicted by Hidden Valley models with a new, confining force with a large 't Hooft coupling. In events with boosted topologies, selected by high-threshold hadronic triggers, the multiplicity and sphericity of clustered tracks are used to reject the background from standard model quantum chromodynamics. With no observed excess of events over the standard model expectation, limits are set on the cross section for production via gluon fusion of a scalar mediator with SUEP-like decays.
The number of observed events as a function of the number of tracks in the SUEP candidate, for all CRs (A–H) and the SR, as well as two signal samples. The three figures correspond to contiguous $S_{boosted}^{SUEP}$ ranges. The VR is not used in the fit so the estimation comes from the observed values in the control regions. For all other regions and bins, the post-fit values for a background-only fit are shown.
The observed exclusions for the nominal $\sigma$ cross section in the plane of $m_{\phi}$ and $T_D$, for various $m_S$ values, for the case $m_{A'}=1.0$ GeV ($A' \rightarrow \pi^+\pi^-$ with $\mathcal{BR}=100\%$).
The expected exclusions for the nominal $\sigma$ cross section in the plane of $m_{\phi}$ and $T_D$, for various $m_S$ values, for the case $m_{A'}=1.0$ GeV ($A' \rightarrow \pi^+\pi^-$ with $\mathcal{BR}=100\%$).
A search for Higgs boson pair (HH) production with one Higgs boson decaying to two bottom quarks and the other to two W bosons are presented. The search is done using proton-proton collisions data at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb$^{-1}$ recorded by the CMS detector at the LHC from 2016 to 2018. The final states considered include at least one leptonically decaying W boson. No evidence for the presence of a signal is observed and corresponding upper limits on the HH production cross section are derived. The limit on the inclusive cross section of the nonresonant HH production, assuming that the distributions of kinematic observables are as expected in the standard model (SM), is observed (expected) to be 14 (18) times the value predicted by the SM, at 95% confidence level. The limits on the cross section are also presented as functions of various Higgs boson coupling modifiers, and anomalous Higgs boson coupling scenarios. In addition, limits are set on the resonant HH production via spin-0 and spin-2 resonances within the mass range 250-900 GeV.
Observed and expected 95% CL upper limits on the production of new particles X of spin-2 and mass $m_X$ in the range 250 $\leq m_X \leq$ 900 GeV, which decay to Higgs boson pairs.
Observed and expected 95% CL upper limits on the production of new particles X of spin-0 and mass $m_X$ in the range 250 $\leq m_X \leq$ 900 GeV, which decay to Higgs boson pairs.
Observed and expected 95% CL upper limits on the inclusive nonresonant HH production cross section obtained for both single-lepton and dilepton channels, and from their combination
A search is presented for the decay of the 125 GeV Higgs boson (H) to a pair of new light pseudoscalar bosons (a), followed by the prompt decay of each a boson to a bottom quark-antiquark pair, H $\to$ aa $\to$$\mathrm{b\bar{b}b\bar{b}}$. The analysis is performed using a data sample of proton-proton collisions collected with the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb$^{-1}$. To reduce the background from standard model processes, the search requires the Higgs boson to be produced in association with a leptonically decaying W or Z boson. The analysis probes the production of new light bosons in a 15 $\lt$$m_\mathrm{a}$$\lt$ 60 GeV mass range. Assuming the standard model predictions for the Higgs boson production cross sections for pp $\to$ WH and ZH, model independent upper limits at 95% confidence level are derived for the branching fraction $\mathcal{B}$(H $\to$ aa $\to$ $\mathrm{b\bar{b}b\bar{b}}$). The combined WH and ZH observed upper limit on the branching fraction ranges from 1.10 for $m_\mathrm{a} =$ 20 GeV to 0.36 for $m_\mathrm{a} =$ 60 GeV, complementing other measurements in the $\mu\mu\tau\tau$, $\tau\tau\tau\tau$ and bb$\ell\ell$ ($\ell = $ $\mu$, $\tau$) channels.
Post-fit BDT distributions in the WH channel extracted with the ma = 60 GeV signal hypothesis. Signal regions for the 3b (upper) and 4b (lower) event categories are shown separately for the electron (left) and muon (right) channels. The dotted lines WH20 GeV, WH60 GeV, illustrate the shapes of the signal template normalised to the SM cross section times a branching fraction B(H → aa → bbbb) = 1 and scaled by the factors indicated in the figure. The horizontal error bars indicate the bin width.
Post-fit BDT distributions in the ZH channel extracted with the ma = 60 GeV signal hypothesis. Signal regions for the 3b (upper) and 4b (lower) event categories are shown separately for the electron (left) and muon (right) channels. The dotted lines ZH20 GeV and ZH60 GeV, illustrate the shapes of the signal template normalised to the SM cross section times a branching fraction B(H → aa → bbbb) = 1 and scaled by the factors indicated in the figure. The horizontal error bars indicate the bin width.
Model independent 95% CL upper limits on σ(VH) B(H → aa → bbbb)/σ(SM) for the WH channel (upper), the ZH channel (middle), and the combination of both channels (lower), where “a” is a new pseudoscalar particle decaying through a → bb, and σ(SM) is the SM Higgs boson production cross section.
The J/$\psi$$\to$$\mu^+\mu^-\mu^+\mu^-$ decay has been observed with a statistical significance in excess of five standard deviations. The analysis is based on an event sample of proton-proton collisions at a center-of-mass energy of 13 TeV, collected by the CMS experiment in 2018 and corresponding to an integrated luminosity of 33.6 fb$^{-1}$. Normalizing to the J/$\psi$$\to$$\mu^+\mu^-$ decay mode leads to a branching fraction [10.1 $^{+3.3}_{-2.7}$ (stat) $\pm$ 0.4 (syst)] $\times$ 10$^{-7}$, a value that is consistent with the standard model prediction.
$\mathrm{J}\mspace{-2mu}/\mspace{-2mu}\psi \to \mu\mu\mu\mu$ branching fraction
$\mathcal{B}(\mathrm{J}\mspace{-2mu}/\mspace{-2mu}\psi \to \mu\mu\mu\mu)$ / $\mathcal{B}(\mathrm{J}\mspace{-2mu}/\mspace{-2mu}\psi \to \mu\mu)$ ratio
A search for ZZ and ZH production in the $\mathrm{b\bar{b}b\bar{b}}$ final state is presented, where H is the standard model (SM) Higgs boson. The search uses an event sample of proton-proton collisions corresponding to an integrated luminosity of 133 fb$^{-1}$ collected at a center-of-mass energy of 13 TeV with the CMS detector at the CERN LHC. The analysis introduces several novel techniques for deriving and validating a multi-dimensional background model based on control samples in data. A multiclass multivariate classifier customized for the $\mathrm{b\bar{b}b\bar{b}}$ final state is developed to derive the background model and extract the signal. The data are found to be consistent, within uncertainties, with the SM predictions. The observed (expected) upper limits at 95% confidence level are found to be 3.8 (3.8) and 5.0 (2.9) times the SM prediction for the ZZ and ZH production cross sections, respectively.
Expected and observed ZZ and ZH signal strengths and their corresponding 95% CL upper limits. The upper limits are obtained from a fit to the SvB signal probabilities under the hypothesis of no ZZ->4b or ZH->4b signal.
Diboson production in association with jets is studied in the fully leptonic final states, pp $\to$ (Z$\gamma^*$)(Z/$\gamma^*$) + jets $\to$ 2$\ell$2$\ell'$ + jets, ($\ell,\ell'$ = e or $\mu$) in proton-proton collisions at a center-of-mass energy of 13 TeV. The data sample corresponds to an integrated luminosity of 138 fb$^{-1}$ collected with the CMS detector at the LHC. Differential distributions and normalized differential cross sections are measured as a function of jet multiplicity, transverse momentum $p_\mathrm{T}$, pseudorapidity $\eta$, invariant mass and $\Delta\eta$ of the highest-$p_\mathrm{T}$ and second-highest-$p_\mathrm{T}$ jets, and as a function of invariant mass of the four-lepton system for events with various jet multiplicities. These differential cross sections are compared with theoretical predictions that mostly agree with the experimental data. However, in a few regions we observe discrepancies between the predicted and measured values. Further improvement of the predictions is required to describe the ZZ + jets production in the whole phase space.
Differential cross sections normalized to the fiducial cross section as a function of the invariant mass of the four-lepton system, in the on-shell ZZ region
Differential cross sections normalized to the fiducial cross section as a function of the number of jets with $p_T > 30$ GeV
Differential cross sections normalized to the fiducial cross section as a function of the $p_T$ of the highest-$p_T$ jet
Searches for pair-produced multijet signatures using data corresponding to an integrated luminosity of 128 fb$^{-1}$ of proton-proton collisions at $\sqrt{s}$ = 13 TeV are presented. A data scouting technique is employed to record events with low jet scalar transverse momentum sum values. The electroweak production of particles predicted in $R$-parity violating supersymmetric models is probed for the first time with fully hadronic final states. This is the first search for prompt hadronically decaying mass-degenerate higgsinos, and extends current exclusions on $R$-parity violating top squarks and gluinos.
Fit results for the pair produced merged three-quark average jet mass ($\bar{m}$) distribution, after the selection of $p_{\rm T}>300$ GeV, $|\eta|<2.4$, and $\tau_{32,\mathrm{DDT}}<0$ on both leading and subleading jet and $A_m<0.15$
Fit results for the pair produced merged three-quark average jet mass ($\bar{m}$) distribution, after the selection of $p_{\rm T}>300$ GeV, $|\eta|<2.4$, and $N^1_{2,\mathrm{DDT}}<0$ on both leading and subleading jet
Fit results for the region 1 of pair produced resolved three jet mass ($m_{jjj}$) distribution, after $H_{\rm T}>600$ GeV, $|\eta|<2.4$, sixth jet $p_{\rm T}>40$ GeV, $D^2_{[(6,3)+(3,2)]}<1.25$, $A_m <0.25$, $\Delta>250$ GeV, $D^2_{[3,2]}<0.05$
A search for Higgs boson pair (HH) production in association with a vector boson V (W or Z boson) is presented. The search is based on proton-proton collision data at a center-of-mass energy of 13 TeV, collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 138 fb$^{-1}$. Both hadronic and leptonic decays of V bosons are used. The leptons considered are electrons, muons, and neutrinos. The HH production is searched for in the $\mathrm{b\bar{b}b\bar{b}}$ decay channel. An observed (expected) upper limit at 95% confidence level of VHH production cross section is set at 294 (124) times the standard model prediction. Constraints are also set on the modifiers of the Higgs boson trilinear self-coupling, $\kappa_{\lambda}$, assuming $\kappa_{2\mathrm{V}}$ = 1 and vice versa on the coupling of two Higgs bosons with two vector bosons, $\kappa_{2\mathrm{V}}$. The observed (expected) 95% confidence intervals of these coupling modifiers are -37.7 $\lt$ $\kappa_{\lambda}$ $\lt$ 37.2 (-30.1 $\lt$ $\kappa_{\lambda}$ $\lt$ 28.9) and -12.2 $\lt$ $\kappa_{2\mathrm{V}}$ $\lt$ 13.5 (-7.2 $\lt$ $\kappa_{2\mathrm{V}}$ $\lt$ 8.9), respectively.
The VHH cross section limits per channel and combined for SM value couplings.
The VHH cross section limits per channel and combined for $\kappa_{\lambda}$ = 5.5.
Upper 95% CL limits on VHH signal cross section scanned over the $\kappa_{\lambda}$ parameter while fixing the $\kappa_{2V}$ and $\kappa_{V}$ to their SM-predicted values.
A measurement is presented of a ratio observable that provides a measure of the azimuthal correlations among jets with large transverse momentum $p_\mathrm{T}$. This observable is measured in multijet events over the range of $p_\mathrm{T}$ = 360-3170 GeV based on data collected by the CMS experiment in proton-proton collisions at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 134 fb$^{-1}$. The results are compared with predictions from Monte Carlo parton-shower event generator simulations, as well as with fixed-order perturbative quantum chromodynamics (pQCD) predictions at next-to-leading-order (NLO) accuracy obtained with different parton distribution functions (PDFs) and corrected for nonperturbative and electroweak effects. Data and theory agree within uncertainties. From the comparison of the measured observable with the pQCD prediction obtained with the NNPDF3.1 NLO PDFs, the strong coupling at the Z boson mass scale is $\alpha_\mathrm{S}(m_\mathrm{Z})$ = 0.1177 $\pm$ 0.0013 (exp) $_{-0.0073}^{+0.0116}$ (theo) = 0.1177 $_{-0.0074}^{+0.0117}$, where the total uncertainty is dominated by the scale dependence of the fixed-order predictions. A test of the running of $\alpha_\mathrm{S}(m_\mathrm{Z})$ in the TeV region shows no deviation from the expected NLO pQCD behaviour.
Bin-to-bin correlation matrix for the $R_{\Delta\phi}(p_\mathrm{T})$ distribution at the particle level.
The $R_{\Delta\phi}(p_\mathrm{T})$ distribution at the particle level as a function of $p_\mathrm{T}$.
Nonperturbative corrections for the $R_{\Delta\phi}(p_\mathrm{T})$ distribution.
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