Search for associated production of a $Z$ boson with an invisibly decaying Higgs boson or dark matter candidates at $\sqrt{s}=13$ TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Braden Keim ; Abbott, Dale ; et al.
Phys.Lett.B 829 (2022) 137066, 2022.
Inspire Record 1969392 DOI 10.17182/hepdata.114363

A search for invisible decays of the Higgs boson as well as searches for dark matter candidates, produced together with a leptonically decaying $Z$ boson, are presented. The analysis is performed using proton-proton collisions at a centre-of-mass energy of 13 TeV, delivered by the LHC, corresponding to an integrated luminosity of 139 fb$^{-1}$ and recorded by the ATLAS experiment. Assuming Standard Model cross-sections for $ZH$ production, the observed (expected) upper limit on the branching ratio of the Higgs boson to invisible particles is found to be 19% (19%) at the 95% confidence level. Exclusion limits are also set for simplified dark matter models and two-Higgs-doublet models with an additional pseudoscalar mediator.

28 data tables

The expected exclusion contours as a function of (m(med), m($\chi$)), with Axial-vector mediator)

The observed exclusion contours as a function of (m(med), m($\chi$)), with Axial-vector mediator)

The expected exclusion contours as a function of (m(med), m($\chi$)), with Vector mediator)

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Search for heavy pseudoscalar and scalar bosons decaying to a top quark pair in proton-proton collisions at $\sqrt{s}$ = 13 TeV

The CMS collaboration Hayrapetyan, Aram ; Makarenko, Vladimir ; Tumasyan, Armen ; et al.
CMS-HIG-22-013, 2025.
Inspire Record 2942928 DOI 10.17182/hepdata.159298

A search for pseudoscalar or scalar bosons decaying to a top quark pair ($\mathrm{t\bar{t}}$) in final states with one or two charged leptons is presented. The analyzed proton-proton collision data was recorded at $\sqrt{s}$ = 13 TeV by the CMS experiment at the CERN LHC and corresponds to an integrated luminosity of 138 fb$^{-1}$. The invariant mass $m_\mathrm{t\bar{t}}$ of the reconstructed $\mathrm{t\bar{t}}$ system and variables sensitive to its spin and parity are used to discriminate against the standard model $\mathrm{t\bar{t}}$ background. Interference between pseudoscalar or scalar boson production and the standard model $\mathrm{t\bar{t}}$ continuum is included, leading to peak-dip structures in the $m_\mathrm{t\bar{t}}$ distribution. An excess of the data above the background prediction, based on perturbative quantum chromodynamics (QCD) calculations, is observed near the kinematic $\mathrm{t\bar{t}}$ production threshold, while good agreement is found for high $m_\mathrm{t\bar{t}}$. The data are consistent with the background prediction if the contribution from the production of a color-singlet ${}^1\mathrm{S}_0^{[1]}$$\mathrm{t\bar{t}}$ quasi-bound state $η_\mathrm{t}$, predicted by nonrelativistic QCD, is added. Upper limits at 95% confidence level are set on the coupling between the pseudoscalar or scalar bosons and the top quark for boson masses in the range 365$-$1000 GeV, relative widths between 0.5 and 25%, and two background scenarios with or without $η_\mathrm{t}$ contribution.

972 data tables

Observed values of twice the negative log-likelihood with respect to the SM (corresponding to $g_{A t \bar t} = g_{H t \bar t} = 0$) for the simultaneous presence of A, $m_A = 450$ GeV, $\Gamma_A/m_A = 5.0$% and H, $m_H = 400$ GeV, $\Gamma_H/m_H = 2.0$% as a function of the coupling modifiers $g_{A t \bar t}$ and $g_{H t \bar t}$.

Observed values of twice the negative log-likelihood with respect to the SM (corresponding to $g_{A t \bar t} = g_{H t \bar t} = 0$) for the simultaneous presence of A, $m_A = 450$ GeV, $\Gamma_A/m_A = 21.0$% and H, $m_H = 700$ GeV, $\Gamma_H/m_H = 2.0$% as a function of the coupling modifiers $g_{A t \bar t}$ and $g_{H t \bar t}$.

Observed values of twice the negative log-likelihood with respect to the SM (corresponding to $g_{A t \bar t} = g_{H t \bar t} = 0$) for the simultaneous presence of A, $m_A = 450$ GeV, $\Gamma_A/m_A = 5.0$% and H, $m_H = 400$ GeV, $\Gamma_H/m_H = 5.0$% as a function of the coupling modifiers $g_{A t \bar t}$ and $g_{H t \bar t}$.

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