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.
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 target asymmetry T, recoil asymmetry P, and beam-target double polarization observable H were determined in exclusive $\pi ^0$ and $\eta $ photoproduction off quasi-free protons and, for the first time, off quasi-free neutrons. The experiment was performed at the electron stretcher accelerator ELSA in Bonn, Germany, with the Crystal Barrel/TAPS detector setup, using a linearly polarized photon beam and a transversely polarized deuterated butanol target. Effects from the Fermi motion of the nucleons within deuterium were removed by a full kinematic reconstruction of the final state invariant mass. A comparison of the data obtained on the proton and on the neutron provides new insight into the isospin structure of the electromagnetic excitation of the nucleon. Earlier measurements of polarization observables in the $\gamma p \rightarrow \pi ^0 p$ and $\gamma p \rightarrow \eta p$ reactions are confirmed. The data obtained on the neutron are of particular relevance for clarifying the origin of the narrow structure in the $\eta n$ system at $W = 1.68\ \textrm{GeV}$. A comparison with recent partial wave analyses favors the interpretation of this structure as arising from interference of the $S_{11}(1535)$ and $S_{11}(1650)$ resonances within the $S_{11}$-partial wave.
Target asymmetry T, recoil asymmetry P, and polarization observable H for $\gamma p \to \pi^0 p$ as a function of the polar center-of-mass angle for bins at the given centroid c.m. energies.
Target asymmetry T, recoil asymmetry P, and polarization observable H for $\gamma n \to \pi^0 n$ as a function of the polar center-of-mass angle for bins at the given centroid c.m. energies.
Target asymmetry T, recoil asymmetry P, and polarization observable H for $\gamma p \to \eta p$ as a function of the polar center-of-mass angle for bins at the given centroid c.m. energies.
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