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A<sc>bstract</sc> A search for Higgs boson (H) production at high transverse momentum (p_T) in the WW decay channel is presented. The analysis uses proton-proton collisions at$$ \sqrt{s}=13 $$ $\sqrt{s}=13$ TeV recorded by the CMS experiment in 2016–2018, corresponding to an integrated luminosity of 138 fb⁻¹. The visible decay products of the Higgs boson are reconstructed as a single large-radius jet with one isolated lepton or none (1ℓand 0ℓ, respectively;ℓ= e,μ). The H-candidate jets are identified using an advanced transformer-based algorithm and are calibrated with the Lund jet plane reweighting technique. The 1ℓchannel is further split into gluon fusion, vector boson fusion, and associated production with hadronically decaying vector boson categories, while the 0ℓchannel considers all production processes inclusively. The measured cross section times the H→WW branching fraction relative to the standard model expectation is$$ \mu =-{0.19}_{-0.46}^{+0.48} $$ $\mu =-{0.19}_{-0.46}^{+0.48}$ , indicating no evidence of a signal above the background. This measurement represents the first dedicated study of highly Lorentz-boosted H→WW decays, complementing earlier searches for high-p_THiggs boson in other decay channels. 

A search for the pair production of heavy spin- $1/2$ or spin- $3/2$ resonances ( $t^{*}$ ) in proton-proton collisions at $\sqrt{s}=13\mathrm{TeV}$ is presented. Data collected with the CMS detector at the CERN LHC from 2016 to 2018 corresponding to an integrated luminosity of $138{\mathrm{fb}}^{-1}$ are used. The analysis targets benchmark signal scenarios where one $t^{*}$ decays into a top quark ( $t$ ) and a photon ( $\gamma$ ), and the other into a $t$ quark and a gluon ( $g$ ), i.e., $pp\to t^{*}\overline{t^{*}}\to tt\gamma g$ . All-hadronic final states from the $t$ pair decay chain are selected using jet substructure techniques. The signal is probed as a function of the $t^{*}$ candidate mass, which is reconstructed using the photon and a top quark candidate jet. No significant deviation from the background-only hypothesis is found. Observed (expected) upper limits on the signal cross section at 95% confidence level are set, excluding masses of spin- $1/2$ $t^{*}$ particles below 930 (930) GeV and spin- $3/2$ $t^{*}$ particles below 1330 (1390) GeV. This analysis marks the first search for heavy resonances in the $t\overline{t}\gamma g$ channel. Exploiting the high-energy photon to reduce the backgrounds, this search achieves sensitivity competitive with $pp\to t^{*}\overline{t^{*}}\to t\overline{t}gg$ searches for spin- $1/2$ $t^{*}$ despite the small expected $t^{*}\to t\gamma$ branching fraction. 

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 $\sqrt{s_{\mathrm{NN}}}=5.36\mathrm{TeV}$ correspond to integrated luminosities of $6.1{\mathrm{nb}}^{-1}$ and $1.02{\mathrm{pb}}^{-1}$ , respectively. The $R_{\mathrm{AA}}$ is below unity with a minimum of $0.69\pm 0.04$ around $p_{\mathrm{T}}=6\mathrm{GeV}$ . The data exhibit better agreement with theoretical models incorporating parton energy loss as compared to baseline models without energy loss. 

Abstract This paper presents a search for new physics through the process where a massive particle, X, decays into a Higgs boson and a second particle, Y. The Higgs boson subsequently decays into a bottom quark–antiquark pair, which is reconstructed as a single large-radius jet. The decay products of Yare also assumed to produce a single large-radius jet. The identification of the Yparticle is enhanced by computing the anomaly score of its candidate jet using an autoencoder, which measures deviations from typical quark- or gluon-induced jets. This allows a simultaneous search for multiple Ydecay scenarios within a single analysis. In the main benchmark process, Yis a scalar particle that decays into a Wboson pair. Two other scalar Ydecay processes are also considered as benchmarks: decays to a light quark–antiquark pair, and decays to a top quark–antiquark pair. A fourth benchmark process considers Yas a hadronically decaying top quark, arising from the decay of a vector-like quark into a top quark and a Higgs boson. Data recorded by the CMS experiment at a center-of-mass energy of 13$$\,\text {Te}\hspace{-.08em}\text {V}$$ $\text{Te}\text{V}$ in 2016–2018, corresponding to an integrated luminosity of 138$$\,\text {fb}^{-1}$$ ${\text{fb}}^{-1}$ , are analyzed. The search covers Xmasses between 1.4 and 3.0$$\,\text {Te}\hspace{-.08em}\text {V}$$ $\text{Te}\text{V}$ and Ymasses between 90 and 400$$\,\text {Ge}\hspace{-.08em}\text {V}$$ $\text{Ge}\text{V}$ , with all simulated signals produced in the narrow-width approximation. No significant excess above the standard model background expectation is observed. The most stringent upper limits to date are placed on benchmark signal cross sections for various masses of X and Y particles 

A search for long-lived particles originating from the decay of $b$ hadrons produced in proton-proton collisions with a center-of-mass energy of 13 TeV at the LHC is presented. The analysis is performed on a dataset recorded in 2018, corresponding to an integrated luminosity of $41.6{\mathrm{fb}}^{-1}$ . Interactions of the long-lived particles in the CMS endcap muon system would create hadronic or electromagnetic showers, producing clusters of detector hits. Selected events contain at least one such high-multiplicity cluster in the muon endcaps and require the presence of a displaced muon. The most stringent upper limits to date on the branching fraction $\mathcal{B}(B\to K\mathrm{\Phi })$ , where the long-lived particle $\mathrm{\Phi }$ decays to a pair of hadrons, are obtained for $\mathrm{\Phi }$ masses of 0.3–3.0 GeV and $\mathrm{\Phi }$ mean proper decay lengths in the range of 1–500 cm. 

Using proton-proton collision data collected by the CMS experiment at $\sqrt{s}=13\mathrm{TeV}$ in 2016–2018, corresponding to an integrated luminosity of $140{\mathrm{fb}}^{-1}$ , the first full reconstruction of the three vector $B$ meson states, $B^{*+}$ , $B^{*0}$ , and $B_s^{*0}$ , is performed. The mass differences between the excited mesons and their corresponding ground states are measured to be $m\left(B^{*+}\right)-m\left(B^{+}\right)=45.277\pm 0.039\pm 0.027\mathrm{MeV}$ , $m\left(B^{*0}\right)-m\left(B^0\right)=45.471\pm 0.056\pm 0.028\mathrm{MeV}$ , and $m\left(B_s^{*0}\right)-m\left(B_s^0\right)=49.407\pm 0.132\pm 0.041\mathrm{MeV}$ , where the first uncertainties are statistical and the second are systematic. These results improve on the precision of previous measurements by an order of magnitude. 

A search for the standard model Higgs boson decaying to a charm quark-antiquark pair, $H\to c\overline{c}$ , produced in association with a top quark-antiquark pair ( $t\overline{t}H$ ) is presented. The search is performed with data from proton-proton collisions at $\sqrt{s}=13\mathrm{TeV}$ , corresponding to an integrated luminosity of $138{\mathrm{fb}}^{-1}$ . Advanced machine learning techniques are employed for jet flavor identification and event classification. The Higgs boson decay to a bottom quark-antiquark pair is measured simultaneously and the observed $t\overline{t}H\left(H\to b\overline{b}\right)$ event rate relative to the standard model expectation is ${0.91}_{-0.22}^{+0.26}$ . The observed (expected) upper limit on the product of production cross section and branching fraction $\sigma \left(t\overline{t}H\right)\mathcal{B}(H\to c\overline{c})$ is 0.11 (0.13) pb at 95% confidence level, corresponding to 7.8 (8.7) times the standard model prediction. When combined with the previous search for $H\to c\overline{c}$ via associated production with a $W$ or $Z$ boson, the observed (expected) 95% confidence interval on the Higgs-charm Yukawa coupling modifier, ${\kappa }_c$ , is $\left|{\kappa }_c\right|<3.5$ (2.7), the most stringent constraint to date. 

Abstract The traditional quark model^1,2accounts for the existence of baryons, such as protons and neutrons, which consist of three quarks, as well as mesons, composed of a quark–antiquark pair. Only recently has substantial evidence started to accumulate for exotic states composed of four or five quarks and antiquarks³. The exact nature of their internal structure remains uncertain^4–29. Here we report the first measurement of quantum numbers of the recently discovered family of three all-charm tetraquarks^30–32, using data collected by the CMS experiment at the Large Hadron Collider from 2016 to 2018 (refs. ^33,34). The angular analysis techniques developed for the discovery and characterization of the Higgs boson^35–37have been applied to the new exotic states. Here we show that the quantum numbers for parityPand charge conjugationCsymmetries are found to be +1. The spinJof these exotic states is determined to be consistent with 2ħ, while 0ħand 1ħare excluded at 95% and 99% confidence levels, respectively. TheJ^PC = 2⁺⁺assignment implies particular configurations of constituent spins and orbital angular momenta, which constrain the possible internal structure of these tetraquarks.