322 Search Results

A search is presented for rare decays of the Z and Higgs bosons to a photon and a J∕ψ or a ψ(2S) meson, with the charmonium state subsequentially decaying to a pair of muons. The data set corresponds to an integrated luminosity of 123 fb⁻¹ of proton-proton collisions at a center-of-mass energy of 13TeV collected with the CMS detector at the LHC. No evidence for branching fractions of these rare decay channels larger than predicted in the standard model is observed. Upper limits at 95% confidence level are set: $$\mathcal{B}$$(H → J∕ψγ ) < 2.6 × 10⁻⁴, $$\mathcal{B}$$(H → ψ(2S)γmore » ) < 9.9 × 10⁻⁴, $$\mathcal{B}$$(Z → J∕ψγ ) < 0.6 × 10⁻⁶, and $$\mathcal{B}$$(Z → ψ(2S)γ ) < 1.3 × 10⁻⁶. The ratio of the Higgs boson coupling modifiers 𝜅_c∕𝜅_γ is constrained to be in the interval (−157, +199) at 95% confidence level. Assuming 𝜅_γ = 1, this interval becomes (−166, +208).« less

A measurement is performed of Higgs bosons produced with high transverse momentum (p$$_{T}$$) via vector boson or gluon fusion in proton-proton collisions. The result is based on a data set with a center-of-mass energy of 13 TeV collected in 2016–2018 with the CMS detector at the LHC and corresponds to an integrated luminosity of 138 fb$$^{−1}$$. The decay of a high-p$$_{T}$$ Higgs boson to a boosted bottom quark-antiquark pair is selected using large-radius jets and employing jet substructure and heavy-flavor taggers based on machine learning techniques. Independent regions targeting the vector boson and gluon fusion mechanisms are defined based onmore » the topology of two quark-initiated jets with large pseudorapidity separation. The signal strengths for both processes are extracted simultaneously by performing a maximum likelihood fit to data in the large-radius jet mass distribution. The observed signal strengths relative to the standard model expectation are $$ {4.9}_{-1.6}^{+1.9} $$ and $$ {1.6}_{-1.5}^{+1.7} $$ for the vector boson and gluon fusion mechanisms, respectively. A differential cross section measurement is also reported in the simplified template cross section framework.[graphic not available: see fulltext]« less

Searches for pair-produced multijet signatures using data corresponding to an integrated luminosity of $128{\mathrm{fb}}^{-1}$ of proton-proton collisions at $\sqrt{s}=13\mathrm{TeV}$ 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, andmore » extends current exclusions on $R$ -parity violating top squarks and gluinos.« less

This paper describes the Combine software package used for statistical analyses by the CMS Collaboration. The package, originally designed to perform searches for a Higgs boson and the combined analysis of those searches, has evolved to become the statistical analysis tool presently used in the majority of measurements and searches performed by the CMS Collaboration. It is not specific to the CMS experiment, and this paper is intended to serve as a reference for users outside of the CMS Collaboration, providing an outline of the most salient features and capabilities. Readers are provided with the possibility to run Combine andmore » reproduce examples provided in this paper using a publicly available container image. Since the package is constantly evolving to meet the demands of ever-increasing data sets and analysis sophistication, this paper cannot cover all details of Combine. However, the online documentation referenced within this paper provides an up-to-date and complete user guide.« less

Diboson production in association with jets is studied in the fully leptonic final states, pp → (Z/γ$$^{*}$$)(Z/γ$$^{*}$$) + jets → 2ℓ2ℓ′ + jets, (ℓ, ℓ′ = e or μ) 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$$_{T}$$, pseudorapidity η, invariant mass and ∆η of the highest-p$$_{T}$$ and second-highest-p$$_{T}$$ jets, and as a function of invariant mass of the four-lepton system formore » 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.« less

Using proton–proton collision data corresponding to an integrated luminosity of $$140\hbox { fb}^{-1}$$ collected by the CMS experiment at $$\sqrt{s}= 13\,\text {Te}\hspace{-.08em}\text {V} $$, the $${{{\Lambda }} _{\text {b}}^{{0}}} \rightarrow {{\text {J}/\uppsi }} {{{\Xi }} ^{{-}}} {{\text {K}} ^{{+}}} $$ decay is observed for the first time, with a statistical significance exceeding 5 standard deviations. The relative branching fraction, with respect to the $${{{\Lambda }} _{\text {b}}^{{0}}} \rightarrow {{{\uppsi }} ({2\textrm{S}})} {{\Lambda }} $$ decay, is measured to be $$\mathcal {B}({{{\Lambda }} _{\text {b}}^{{0}}} \rightarrow {{\text {J}/\uppsi }} {{{\Xi }} ^{{-}}} {{\text {K}} ^{{+}}} )/\mathcal {B}({{{\Lambda }} _{\text {b}}^{{0}}} \rightarrowmore » {{{\uppsi }} ({2\textrm{S}})} {{\Lambda }} ) = [3.38\pm 1.02\pm 0.61\pm 0.03]\%$$, where the first uncertainty is statistical, the second is systematic, and the third is related to the uncertainties in $$\mathcal {B}({{{\uppsi }} ({2\textrm{S}})} \rightarrow {{\text {J}/\uppsi }} {{{\uppi }} ^{{+}}} {{{\uppi }} ^{{-}}} )$$ and $$\mathcal {B}({{{\Xi }} ^{{-}}} \rightarrow {{\Lambda }} {{{\uppi }} ^{{-}}} )$$.« less

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 $$ \textrm{b}\overline{\textrm{b}}\textrm{b}\overline{\textrm{b}} $$ decay channel. An observed (expected) upper limit at 95% confidence level of VHH production cross section is set atmore » 294 (124) times the standard model prediction. Constraints are also set on the modifiers of the Higgs boson trilinear self-coupling, k$$_{λ}$$, assuming k$$_{2V}$$ = 1, and vice versa on the coupling of two Higgs bosons with two vector bosons, k$$_{2V}$$. The observed (expected) 95% confidence intervals of these coupling modifiers are −37.7 < k$$_{λ}$$ < 37.2 (−30.1 < k$$_{λ}$$ < 28.9) and −12.2 < k$$_{2V}$$ < 13.5 (−7.2 < k$$_{2V}$$ < 8.9), respectively.[graphic not available: see fulltext]« less

A search for electroweak production of a single vectorlike $T$ quark in association with a bottom ( $b$ ) quark in the all-hadronic decay channel is presented. This search uses proton-proton collision data at $\sqrt{s}=13\mathrm{TeV}$ collected by the CMS experiment at the CERN LHC during 2016–2018, corresponding to an integrated luminosity of $138{\mathrm{fb}}^{-1}$ . The $T$ quark is assumed to have charge $2/3$ and decay to a top ( $t$ ) quark and a Higgs ( $H$ ) ormore » $Z$ boson. Hadronic decays of the $t$ quark and the $H$ or $Z$ boson are reconstructed from the kinematic properties of jets, including those containing $b$ hadrons. No deviation from the standard model prediction is observed in the reconstructed $tH$ and $tZ$ invariant mass distributions. The 95% confidence level upper limits on the product of the production cross section and branching fraction of a $T$ quark produced in association with a $b$ quark and decaying via $tH$ or $tZ$ range from 1260 to 68 fb for $T$ quark masses of 600–1200 GeV.« less

The polarizations of prompt and non-prompt Image 2 and $\mathrm{\psi }\left(\mathrm{2S}\right)$ mesons are measured in proton-proton collisions at $\sqrt{s}=13$  TeV, using data samples collected by the CMS experiment in 2017 and 2018, corresponding to a total integrated luminosity of 103.3 ${\text{fb}}^{-1}$ . Based on the analysis of the dimuon decay angular distributions in the helicity frame, the polar anisotropy, ${\lambda }_{\vartheta }$ , is measured as a function of the transverse momentum,more » $p_{\mathrm{T}}$ , of the charmonium states, in the 25–120 and 20–100 GeV ranges for the Image 2 and $\mathrm{\psi }\left(\mathrm{2S}\right)$ , respectively. The non-prompt polarizations agree with predictions based on the hypothesis that, for $p_{\mathrm{T}}\gtrsim 25\text{GeV}$ , the non-prompt Image 2 and $\mathrm{\psi }\left(\mathrm{2S}\right)$ are predominantly produced in two-body B meson decays. The prompt results clearly exclude strong transverse polarizations, even for $p_{\mathrm{T}}$ exceeding 30 times the Image 2 mass, where ${\lambda }_{\vartheta }$ tends to an asymptotic value around 0.3. Taken together with previous measurements, by CMS and LHCb at $\sqrt{s}=7$  TeV, the prompt polarizations show a significant variation with $p_{\mathrm{T}}$ , at low $p_{\mathrm{T}}$ .« less

The performance of muon tracking, identification, triggering, momentum resolution, and momentum scale has been studied with the CMS detector at the LHC using data collected at √(s$$_{NN}$$) = 5.02 TeV in proton-proton (pp) and lead-lead(PbPb) collisions in 2017 and 2018, respectively, and at √(s$$_{NN}$$) = 8.16 TeV in proton-lead (pPb) collisions in 2016. Muon efficiencies, momentum resolutions, and momentum scales are compared by focusing on how the muon reconstruction performance varies from relatively small occupancy pp collisions to the larger occupancies of pPb collisions and, finally, to the highest track multiplicity PbPb collisions. We find the efficiencies of muon tracking,more » identification, and triggering to be above 90% throughout most of the track multiplicity range. The momentum resolution and scale are unaffected by the detector occupancy. The excellent muon reconstruction of the CMS detector enables precision studies across all available collision systems.« less