We search for new massive scalar particles X and Y through the resonant process X $\to$ YH $\to$$\mathrm{b\bar{b}b\bar{b}}$, where H is the standard model Higgs boson. Data from CERN LHC proton-proton collisions are used, collected at a centre-of-mass energy of 13 TeV in 2016-2018 and corresponding to an integrated luminosity of 138 fb$^{-1}$. The search is performed in mass ranges of 0.9-4 TeV for X and 60-600 GeV for Y, where both Y and H are reconstructed as Lorentz-boosted single large-area jets. The results are interpreted in the context of the next-to-minimal supersymmetric standard model and also in an extension of the standard model with two additional singlet scalar fields. The 95% confidence level upper limits for the production cross section vary between 0.1 and 150 fb depending on the X and Y masses, and represent a significant improvement over results from previous searches.
The $M_J^Y$ distribution for the number of observed events (black markers) compared with the estimated backgrounds (filled histograms) and their uncertainties (hatched areas) in the SR1. The distributions expected from the signal under three $M_X$ and $M_Y$ hypotheses and assuming a cross section of 1 fb are also shown. The lower panels show the ''Pulls'' defined as (observed events - expected events)/$\sqrt{\smash[b]{\sigma_{obs}^{2} - \sigma_{exp}^{2}}}$, where $\sigma_{obs}$ and $\sigma_{exp}$ are the statistical and total uncertainties in the observation and the background estimation, respectively. The minus sign accounts for the correlation between data and the data-driven estimation.
The $M_{JJ}$ distribution for the number of observed events (black markers) compared with the estimated backgrounds (filled histograms) and their uncertainties (hatched areas) in the SR1. The distributions expected from the signal under three $M_X$ and $M_Y$ hypotheses and assuming a cross section of 1 fb are also shown. The lower panels show the ''Pulls'' defined as (observed events - expected events)/$\sqrt{\smash[b]{\sigma_{obs}^{2} - \sigma_{exp}^{2}}}$, where $\sigma_{obs}$ and $\sigma_{exp}$ are the statistical and total uncertainties in the observation and the background estimation, respectively. The minus sign accounts for the correlation between data and the data-driven estimation.
The soft-drop mass distribution of the top quark candidate jets in the 2018 jets+lepton category, in the tight ParticleNet region, after the joint fit in all-jets and jets+lepton categories. Observed data (black markers) and the postfit estimate (filled histograms) are shown for the three jet categories. The lower panel shows the ''Pulls'' defined as (observed events - expected events)/$\sqrt{\smash[b]{\sigma_{obs}^{2} + \sigma_{exp}^{2}}}$, where $\sigma_{obs}$ and $\sigma_{exp}$ are the statistical and total uncertainties in the observation and the background estimation, respectively.
A search for heavy resonances decaying into a $W$ or $Z$ boson and a Higgs boson produced in proton$-$proton collisions at the Large Hadron Collider at $\sqrt{s} = 13$ TeV is presented. The analysis utilizes the dominant $W \to q \bar{q}^\prime$ or $Z \to q \bar{q}$ and $H \to b \bar{b}$ decays with substructure techniques applied to large-radius jets. A sample corresponding to an integrated luminosity of 139 fb$^{-1}$ collected with the ATLAS detector is analyzed and no significant excess of data is observed over the background prediction. The results are interpreted in the context of the Heavy Vector Triplet model with spin-1 $W^\prime$ and $Z^\prime$ bosons. Upper limits on the cross section are set for resonances with mass between 1.5 and 5.0 TeV, ranging from 6.8 to 0.53 fb for $W^\prime \to WH$ and from 8.7 to 0.53 fb for $Z^\prime \to ZH$ at the 95 % confidence level.
Observed and expected 95% CL upper limits on the cross section in the WH channel.
Observed and expected 95% CL upper limits on the cross section in the ZH channel.
Signal acceptance times efficiency of HVT WH(qqbb) events as a function of the resonance mass at different cut stages. Auxiliary table attached for 2 TeV mass point.
Observables sensitive to the anomalous production of events containing hadronic jets and missing momentum in the plane transverse to the proton beams at the Large Hadron Collider are presented. The observables are defined as a ratio of cross sections, for events containing jets and large missing transverse momentum to events containing jets and a pair of charged leptons from the decay of a $Z/\gamma^\ast$ boson. This definition minimises experimental and theoretical systematic uncertainties in the measurements. This ratio is measured differentially with respect to a number of kinematic properties of the hadronic system in two phase-space regions; one inclusive single-jet region and one region sensitive to vector-boson-fusion topologies. The data are found to be in agreement with the Standard Model predictions and used to constrain a variety of theoretical models for dark-matter production, including simplified models, effective field theory models, and invisible decays of the Higgs boson. The measurements use 3.2 fb$^{-1}$ of proton--proton collision data recorded by the ATLAS experiment at a centre-of-mass energy of 13 TeV and are fully corrected for detector effects, meaning that the data can be used to constrain new-physics models beyond those shown in this paper.
Measured and expected $R^\text{miss}$ as a function of $p_\text{T}^\text{miss}$ in the $\geq 1$ jet phase space. The fiducial SM predictions for the numerator and the denominator are also given.
Measured and expected $R^\text{miss}$ as a function of $p_\text{T}^\text{miss}$ in the VBF phase space. The fiducial SM predictions for the numerator and the denominator are also given.
Measured and expected $R^\text{miss}$ as a function of $M_\text{jj}$ in the VBF phase space. The fiducial SM predictions for the numerator and the denominator are also given.
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