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1. Search for light Higgs bosons from supersymmetric cascade decays in $$\text {pp}$$ collisions at $$\sqrt{s}=13\,\textrm{TeV}$$

   https://doi.org/10.1140/epjc/s10052-023-11581-0  

   Tumasyan, A. ; Adam, W. ; Andrejkovic, J. W. ; Bergauer, T. ; Chatterjee, S. ; Damanakis, K. ; Dragicevic, M. ; Valle, A. Escalante ; Frühwirth, R. ; Jeitler, M. ; et al ( July 2023 , The European Physical Journal C)

   A search is reported for pairs of light Higgs bosons ($${\textrm{H}} _1$$${\text{H}}_1$) produced in supersymmetric cascade decays in final states with small missing transverse momentum. A data set of LHC$$\hbox {pp}$$$\text{pp}$collisions collected with the CMS detector at$$\sqrt{s}=13\,\text {TeV} $$$\sqrt{s}=13\text{TeV}$and corresponding to an integrated luminosity of 138$$\,\text {fb}^{-1}$$${\text{fb}}^{-1}$is used. The search targets events where both$${\textrm{H}} _1$$${\text{H}}_1$bosons decay into Equation missing<#comment/>pairs that are reconstructed as large-radius jets using substructure techniques. No evidence is found for an excess of events beyond the background expectations of the standard model (SM). Results from the search are interpreted in the next-to-minimal supersymmetric extension of the SM, where a “singlino” of small mass leads to squark and gluino cascade decays that can predominantly end in a highly Lorentz-boosted singlet-like$${\textrm{H}} _1$$${\text{H}}_1$and a singlino-like neutralino of small transverse momentum. Upper limits are set on the product of the squark or gluino pair production cross section and the square of the Equation missing<#comment/>branching fraction of the$${\textrm{H}} _1$$${\text{H}}_1$in a benchmark model containing almost mass-degenerate gluinos and light-flavour squarks. Under the assumption of an SM-like Equation missing<#comment/>branching fraction,$${\textrm{H}} _1$$${\text{H}}_1$bosons with masses in the range 40–120$$\,\text {GeV}$$$\text{GeV}$arising from the decays of squarks or gluinos with a mass of 1200–2500$$\,\text {GeV}$$$\text{GeV}$are excluded at 95% confidence level.

    

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2. Search for Higgs boson decays to a Z boson and a photon in proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV

   https://doi.org/10.1007/JHEP05(2023)233  

   Tumasyan, A. ; Adam, W. ; Andrejkovic, J. W. ; Bergauer, T. ; Chatterjee, S. ; Damanakis, K. ; Dragicevic, M. ; Escalante Del Valle, A. ; Frühwirth, R. ; Jeitler, M. ; et al ( May 2023 , Journal of High Energy Physics)

   Results are presented from a search for the Higgs boson decay H→Zγ, where Z→ ℓ⁺ℓ⁻withℓ= e or μ. The search is performed using a sample of proton-proton (pp) collision data at a center-of-mass energy of 13 TeV, recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 138 fb⁻¹. Events are assigned to mutually exclusive categories, which exploit differences in both event topology and kinematics of distinct Higgs production mechanisms to enhance signal sensitivity. The signal strengthμ, defined as the product of the cross section and the branching fraction$$ \left[\sigma \left(\textrm{pp}\to \textrm{H}\right)\mathcal{B}\left(\textrm{H}\to \textrm{Z}\upgamma \right)\right] $$$\left(\sigma \left(\mathrm{pp}\to H\right)B\left(H\to \mathrm{Z\gamma }\right)\right)$relative to the standard model prediction, is extracted from a simultaneous fit to theℓ⁺ℓ⁻γ invariant mass distributions in all categories and is measured to beμ= 2.4 ± 0.9 for a Higgs boson mass of 125.38 GeV. The statistical significance of the observed excess of events is 2.7 standard deviations. This measurement corresponds to$$ \left[\sigma \left(\textrm{pp}\to \textrm{H}\right)\mathcal{B}\left(\textrm{H}\to \textrm{Z}\upgamma \right)\right]=0.21\pm 0.08 $$$\left(\sigma \left(\mathrm{pp}\to H\right)B\left(H\to \mathrm{Z\gamma }\right)\right)=0.21\pm 0.08$pb. The observed (expected) upper limit at 95% confidence level onμis 4.1 (1.8), where the expected limit is calculated under the background-only hypothesis. The ratio of branching fractions$$ \mathcal{B}\left(\textrm{H}\to \textrm{Z}\upgamma \right)/\mathcal{B}\left(\textrm{H}\to \upgamma \upgamma \right) $$$B\left(H\to \mathrm{Z\gamma }\right)/B\left(H\to \mathrm{\gamma \gamma }\right)$is measured to be$$ {1.5}_{-0.6}^{+0.7} $$${1.5}_{-0.6}^{+0.7}$, which agrees with the standard model prediction of 0.69 ± 0.04 at the 1.5 standard deviation level.

    

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3. A search for decays of the Higgs boson to invisible particles in events with a top-antitop quark pair or a vector boson in proton-proton collisions at $$\sqrt{s} = 13\,\text {Te}\hspace{-.08em}\text {V} $$

   https://doi.org/10.1140/epjc/s10052-023-11952-7  

   Tumasyan, A. ; Adam, W. ; Andrejkovic, J. W. ; Bergauer, T. ; Chatterjee, S. ; Damanakis, K. ; Dragicevic, M. ; Escalante Del Valle, A. ; Hussain, P. S. ; Jeitler, M. ; et al ( October 2023 , The European Physical Journal C)

   A search for decays to invisible particles of Higgs bosons produced in association with a top-antitop quark pair or a vector boson, which both decay to a fully hadronic final state, has been performed using proton-proton collision data collected at$${\sqrt{s}=13\,\text {Te}\hspace{-.08em}\text {V}}$$$\sqrt{s}=13\text{Te}\text{V}$by the CMS experiment at the LHC, corresponding to an integrated luminosity of 138$$\,\text {fb}^{-1}$$${\text{fb}}^{-1}$. The 95% confidence level upper limit set on the branching fraction of the 125$$\,\text {Ge}\hspace{-.08em}\text {V}$$$\text{Ge}\text{V}$Higgs boson to invisible particles,$${\mathcal {B}({\textrm{H}} \rightarrow \text {inv})}$$$B(\text{H}\to \text{inv})$, is 0.54 (0.39 expected), assuming standard model production cross sections. The results of this analysis are combined with previous$${\mathcal {B}({\textrm{H}} \rightarrow \text {inv})}$$$B(\text{H}\to \text{inv})$searches carried out at$${\sqrt{s}=7}$$$\sqrt{s}=7$, 8, and 13$$\,\text {Te}\hspace{-.08em}\text {V}$$$\text{Te}\text{V}$in complementary production modes. The combined upper limit at 95% confidence level on$${\mathcal {B}({\textrm{H}} \rightarrow \text {inv})}$$$B(\text{H}\to \text{inv})$is 0.15 (0.08 expected).

    

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4. Search for pair-produced vector-like top and bottom partners in events with large missing transverse momentum in pp collisions with the ATLAS detector

   https://doi.org/10.1140/epjc/s10052-023-11790-7  

   Aad, G. ; Abbott, B. ; Abbott, D. C. ; Abeling, K. ; Abidi, S. H. ; Aboulhorma, A. ; Abramowicz, H. ; Abreu, H. ; Abulaiti, Y. ; Abusleme Hoffman, A. C. ; et al ( August 2023 , The European Physical Journal C)

   A search for pair-produced vector-like quarks using events with exactly one lepton (eor$$\mu $$$\mu$), at least four jets including at least oneb-tagged jet, and large missing transverse momentum is presented. Data from proton–proton collisions at a centre-of-mass energy of$$\sqrt{s}=$$$\sqrt{s}=$13 $$\text {TeV}$$$\text{TeV}$, recorded by the ATLAS detector at the LHC from 2015 to 2018 and corresponding to an integrated luminosity of 139 fb$$^{-1}$$${}^{-1}$, are analysed. Vector-like partnersTandBof the top and bottom quarks are considered, as is a vector-likeXwith charge$$+5/3$$$+5/3$, assuming their decay into aW,Z, or Higgs boson and a third-generation quark. No significant deviations from the Standard Model expectation are observed. Upper limits on the production cross-section ofTandBquark pairs as a function of their mass are derived for various decay branching ratio scenarios. The strongest lower limits on the masses are 1.59 $$\text {TeV}$$$\text{TeV}$assuming mass-degenerate vector-like quarks and branching ratios corresponding to the weak-isospin doublet model, and 1.47 $$\text {TeV}$$$\text{TeV}$(1.46 $$\text {TeV}$$$\text{TeV}$) for exclusive$$T \rightarrow Zt$$$T\to Zt$($$B/X \rightarrow Wt$$$B/X\to Wt$) decays. In addition, lower limits on theTandBquark masses are derived for all possible branching ratios.

    

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5. Search for Higgs boson pair production in association with a vector boson in pp collisions at $$\sqrt{s}=13\,\text {TeV}$$ with the ATLAS detector

   https://doi.org/10.1140/epjc/s10052-023-11559-y  

   Aad, G. ; Abbott, B. ; Abbott, D. C. ; Abeling, K. ; Abidi, S. H. ; Aboulhorma, A. ; Abramowicz, H. ; Abreu, H. ; Abulaiti, Y. ; Hoffman, A. C. ; et al ( June 2023 , The European Physical Journal C)

   This paper reports a search for Higgs boson pair (hh) production in association with a vector boson ($$W\; {\text {o}r}\; Z$$$W\text{o}rZ$) using 139 fb$$^{-1}$$${}^{-1}$of proton–proton collision data at$$\sqrt{s}=13\,\text {TeV}$$$\sqrt{s}=13\text{TeV}$recorded with the ATLAS detector at the Large Hadron Collider. The search is performed in final states in which the vector boson decays leptonically ($$W\rightarrow \ell \nu ,\, Z\rightarrow \ell \ell ,\nu \nu $$$W\to \ell \nu ,Z\to \ell \ell ,\nu \nu$with$$\ell =e, \mu $$$\ell =e,\mu$) and the Higgs bosons each decay into a pair ofb-quarks. It targetsVhhsignals from both non-resonanthhproduction, present in the Standard Model (SM), and resonanthhproduction, as predicted in some SM extensions. A 95% confidence-level upper limit of 183 (87) times the SM cross-section is observed (expected) for non-resonantVhhproduction when assuming the kinematics are as expected in the SM. Constraints are also placed on Higgs boson coupling modifiers. For the resonant search, upper limits on the production cross-sections are derived for two specific models: one is the production of a vector boson along with a neutral heavy scalar resonanceH, in the mass range 260–1000 GeV, that decays intohh, and the other is the production of a heavier neutral pseudoscalar resonanceAthat decays into aZboson andHboson, where theAboson mass is 360–800 GeV and theHboson mass is 260–400 GeV. Constraints are also derived in the parameter space of two-Higgs-doublet models.

    

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