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1. Measurement of differential ZZ + jets production cross sections in pp collisions at $$ \sqrt{s} $$ = 13 TeV

   https://doi.org/10.1007/JHEP10(2024)209  

   Hayrapetyan, A; Tumasyan, A; Adam, W; Andrejkovic, J W; Bergauer, T; Chatterjee, S; Damanakis, K; Dragicevic, M; Escalante_Del_Valle, A; Hussain, P S; et al (October 2024, Journal of High Energy Physics)

   A<sc>bstract</sc> Diboson production in association with jets is studied in the fully leptonic final states, pp → (Z/γ^*)(Z/γ^*) + jets → 2ℓ2ℓ′ + jets, (ℓ,ℓ′ = e orμ) in proton-proton collisions at a center-of-mass energy of 13 TeV. The data sample corresponds to an integrated luminosity of 138 fb⁻¹collected with the CMS detector at the LHC. Differential distributions and normalized differential cross sections are measured as a function of jet multiplicity, transverse momentump_T, pseudorapidityη, invariant mass and ∆ηof the highest-p_Tand second-highest-p_Tjets, and as a function of invariant mass of the four-lepton system for events with various jet multiplicities. These differential cross sections are compared with theoretical predictions that mostly agree with the experimental data. However, in a few regions we observe discrepancies between the predicted and measured values. Further improvement of the predictions is required to describe the ZZ+jets production in the whole phase space. 

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2. Search for dark matter produced in association with a dark Higgs boson decaying into W+W− in the one-lepton final state at $$ \sqrt{s} $$ = 13 TeV using 139 fb−1 of pp collisions recorded with the ATLAS detector

   https://doi.org/10.1007/JHEP07(2023)116  

   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 (July 2023, Journal of High Energy Physics)

   A<sc>bstract</sc> Several extensions of the Standard Model predict the production of dark matter particles at the LHC. A search for dark matter particles produced in association with a dark Higgs boson decaying intoW⁺W⁻in the$$ {\ell}^{\pm}\nu q{\overline{q}}^{\prime }, $$ ${\ell }^{\pm }\mathrm{\nu q}{\overline{q}}^{\prime },$final states withℓ=e, μis presented. This analysis uses 139 fb⁻¹ofppcollisions recorded by the ATLAS detector at a centre-of-mass energy of 13 TeV. TheW^±→$$ q\overline{q^{\prime }} $$ $q\overline{q\prime }$decays are reconstructed from pairs of calorimeter-measured jets or from track-assisted reclustered jets, a technique aimed at resolving the dense topology from a pair of boosted quarks using jets in the calorimeter and tracking information. The observed data are found to agree with Standard Model predictions. Scenarios with dark Higgs boson masses ranging between 140 and 390 GeV are excluded. 

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3. Measurement of the inclusive cross sections for W and Z boson production in proton-proton collisions at $$ \sqrt{\textrm{s}} $$ = 5.02 and 13 TeV

   https://doi.org/10.1007/JHEP04(2025)162  

   Hayrapetyan, A; Tumasyan, A; Adam, W; Andrejkovic, J W; Bergauer, T; Chatterjee, S; Damanakis, K; Dragicevic, M; Hussain, P S; Jeitler, M; et al (April 2025, Journal of High Energy Physics)

   A<sc>bstract</sc> Measurements of fiducial and total inclusive cross sections for W and Z boson production are presented in proton-proton collisions at$$ \sqrt{s} $$ $\sqrt{s}$= 5.02 and 13 TeV. Electron and muon decay modes (ℓ= e orμ) are studied in the data collected with the CMS detector in 2017, in dedicated runs with reduced instantaneous luminosity. The data sets correspond to integrated luminosities of 298 ± 6 pb⁻¹at 5.02 TeV and 206 ± 5 pb⁻¹at 13 TeV. Measured values of the products of the total inclusive cross sections and the branching fractions at 5.02 TeV areσ(pp→W + X)$$ \mathcal{B} $$ $B$(W→ ℓν) = 7300±10 (stat)±60 (syst)±140 (lumi) pb, andσ(pp→Z+X)$$ \mathcal{B} $$ $B$(Z→ ℓ⁺ℓ⁻) = 669±2 (stat)±6 (syst)±13 (lumi) pb for the dilepton invariant mass in the range of 60–120 GeV. The corresponding results at 13 TeV are 20480±10 (stat)±170 (syst)±470 (lumi) pb and 1952±4 (stat)±18 (syst)±45 (lumi) pb. The measured values agree with cross section calculations at next-to-next-to-leading-order in perturbative quantum chromodynamics. Fiducial and total inclusive cross sections, ratios of cross sections of W⁺and W⁻production as well as inclusive W and Z boson production, and ratios of these measurements at 5.02 and 13 TeV are reported. 

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4. 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)

   A<sc>bstract</sc> 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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5. Search for dark matter particles in W+W− events with transverse momentum imbalance in proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV

   https://doi.org/10.1007/JHEP03(2024)134  

   Hayrapetyan, A; Tumasyan, A; Adam, W; Andrejkovic, J W; Bergauer, T; Chatterjee, S; Damanakis, K; Dragicevic, M; Escalante_Del_Valle, A; Hussain, P S; et al (March 2024, Journal of High Energy Physics)

   A<sc>bstract</sc> A search for dark matter particles is performed using events with a pair of W bosons and large missing transverse momentum. Candidate events are selected by requiring one or two leptons (ℓ= electrons or muons). The analysis is based on proton-proton collision data collected at a center-of-mass energy of 13 TeV by the CMS experiment at the LHC and corresponding to an integrated luminosity of 138 fb⁻¹. No significant excess over the expected standard model background is observed in theℓνqq and 2ℓ2νfinal states of the W⁺W⁻boson pair. Limits are set on dark matter production in the context of a simplified dark Higgs model, with a dark Higgs boson mass above the W⁺W⁻mass threshold. The dark matter phase space is probed in the mass range 100–300 GeV, extending the scope of previous searches. Current exclusion limits are improved in the range of dark Higgs masses from 160 to 250 GeV, for a dark matter mass of 200 GeV. 

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