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1. Search for CP violation in t$$ \overline{\textrm{t}} $$H and tH production in multilepton channels in proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV

   https://doi.org/10.1007/JHEP07(2023)092  

   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 ( July 2023 , Journal of High Energy Physics)

   The charge-parity (CP) structure of the Yukawa interaction between the Higgs (H) boson and the top quark is measured in a data sample enriched in the t$$ \overline{\textrm{t}} $$$\overline{t}$H and tH associated production, using 138 fb⁻¹of data collected in proton-proton collisions at$$ \sqrt{s} $$$\sqrt{s}$= 13 TeV by the CMS experiment at the CERN LHC. The study targets events where the H boson decays via H → WW or H →ττand the top quarks decay via t → Wb: the W bosons decay either leptonically or hadronically, and final states characterized by the presence of at least two leptons are studied. Machine learning techniques are applied to these final states to enhance the separation ofCP-even fromCP-odd scenarios. Two-dimensional confidence regions are set onκ_tand$$ \overset{\sim }{\kappa } $$$\tilde{\kappa }$_t, which are respectively defined as theCP-even andCP-odd top-Higgs Yukawa coupling modifiers. No significant fractionalCP-odd contributions, parameterized by the quantity|$$ {f}_{CP}^{\textrm{Htt}} $$$f_{\mathrm{CP}}^{\mathrm{Htt}}$|are observed; the parameter is determined to be|$$ {f}_{CP}^{\textrm{Htt}} $$$f_{\mathrm{CP}}^{\mathrm{Htt}}$|= 0.59 with an interval of (0.24,0.81) at 68% confidence level. The results are combined with previous results covering the H→ZZ and H→ γγdecay modes, yielding two- and one-dimensional confidence regions onκ_tand$$ \overset{\sim }{\kappa } $$$\tilde{\kappa }$_t, while|$$ {f}_{CP}^{\textrm{Htt}} $$$f_{\mathrm{CP}}^{\mathrm{Htt}}$|is determined to be|$$ {f}_{CP}^{\textrm{Htt}} $$$f_{\mathrm{CP}}^{\mathrm{Htt}}$|= 0.28 with an interval of|$$ {f}_{CP}^{\textrm{Htt}} $$$f_{\mathrm{CP}}^{\mathrm{Htt}}$| <0.55 at 68% confidence level, in agreement with the standard modelCP-even prediction of|$$ {f}_{CP}^{\textrm{Htt}} $$$f_{\mathrm{CP}}^{\mathrm{Htt}}$|= 0.

    

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2. Measurement of the top quark pole mass using $$ \textrm{t}\overline{\textrm{t}} $$+jet events in the dilepton final state in proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV

   https://doi.org/10.1007/JHEP07(2023)077  

   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 ( July 2023 , Journal of High Energy Physics)

   A measurement of the top quark pole mass$$ {m}_{\textrm{t}}^{\textrm{pole}} $$$m_t^{\text{pole}}$in events where a top quark-antiquark pair ($$ \textrm{t}\overline{\textrm{t}} $$$t\overline{t}$) is produced in association with at least one additional jet ($$ \textrm{t}\overline{\textrm{t}} $$$t\overline{t}$+jet) is presented. This analysis is performed using proton-proton collision data at$$ \sqrt{s} $$$\sqrt{s}$= 13 TeV collected by the CMS experiment at the CERN LHC, corresponding to a total integrated luminosity of 36.3 fb⁻¹. Events with two opposite-sign leptons in the final state (e⁺e⁻,μ⁺μ⁻, e^±μ^∓) are analyzed. The reconstruction of the main observable and the event classification are optimized using multivariate analysis techniques based on machine learning. The production cross section is measured as a function of the inverse of the invariant mass of the$$ \textrm{t}\overline{\textrm{t}} $$$t\overline{t}$+jet system at the parton level using a maximum likelihood unfolding. Given a reference parton distribution function (PDF), the top quark pole mass is extracted using the theoretical predictions at next-to-leading order. For the ABMP16NLO PDF, this results in$$ {m}_{\textrm{t}}^{\textrm{pole}} $$$m_t^{\text{pole}}$= 172.93±1.36 GeV.

    

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3. Search for pair-produced scalar and vector leptoquarks decaying into third-generation quarks and first- or second-generation leptons in pp collisions with the ATLAS detector

   https://doi.org/10.1007/JHEP06(2023)188  

   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 ( June 2023 , Journal of High Energy Physics)

   A search for pair-produced scalar and vector leptoquarks decaying into quarks and leptons of different generations is presented. It uses the full LHC Run 2 (2015–2018) data set of 139 fb⁻¹collected with the ATLAS detector in proton–proton collisions at a centre-of-mass energy of$$ \sqrt{s} $$$\sqrt{s}$= 13 TeV. Scalar leptoquarks with charge −(1/3)eas well as scalar and vector leptoquarks with charge +(2/3)eare considered. All possible decays of the pair-produced leptoquarks into quarks of the third generation (t, b) and charged or neutral leptons of the first or second generation (e, μ, ν) with exactly one electron or muon in the final state are investigated. No significant deviations from the Standard Model expectation are observed. Upper limits on the production cross-section are provided for eight models as a function of the leptoquark mass and the branching ratio of the leptoquark into the charged or neutral lepton. In addition, lower limits on the leptoquark masses are derived for all models across a range of branching ratios. Two of these models have the goal of providing an explanation for the recentB-anomalies. In both models, a vector leptoquark decays into charged and neutral leptons of the second generation with a similar branching fraction. Lower limits of 1980 GeV and 1710 GeV are set on the leptoquark mass for these two models.

    

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4. Search for supersymmetry in final states with missing transverse momentum and three or more b-jets in 139 fb$$^{-1}$$ of proton–proton collisions at $$\sqrt{s} = 13$$ TeV with the ATLAS detector

   https://doi.org/10.1140/epjc/s10052-023-11543-6  

   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 , The European Physical Journal C)

   A search for supersymmetry involving the pair production of gluinos decaying via off-shell third-generation squarks into the lightest neutralino$$(\tilde{\chi }^0_1)$$$\left({\tilde{\chi }}_1^0\right)$is reported. It exploits LHC proton–proton collision data at a centre-of-mass energy$$\sqrt{s} = 13$$$\sqrt{s}=13$TeV with an integrated luminosity of 139 fb$$^{-1}$$${}^{-1}$collected with the ATLAS detector from 2015 to 2018. The search uses events containing large missing transverse momentum, up to one electron or muon, and several energetic jets, at least three of which must be identified as containingb-hadrons. Both a simple kinematic event selection and an event selection based upon a deep neural-network are used. No significant excess above the predicted background is found. In simplified models involving the pair production of gluinos that decay via off-shell top (bottom) squarks, gluino masses less than 2.44 TeV (2.35 TeV) are excluded at 95% CL for a massless$$\tilde{\chi }^0_1.$$${\tilde{\chi }}_1^0.$Limits are also set on the gluino mass in models with variable branching ratios for gluino decays to$$b\bar{b}\tilde{\chi }^0_1,$$$b\overline{b}{\tilde{\chi }}_1^0,$$$t\bar{t}\tilde{\chi }^0_1$$$t\overline{t}{\tilde{\chi }}_1^0$and$$t\bar{b}\tilde{\chi }^-_1/\bar{t}b\tilde{\chi }^+_1.$$$t\overline{b}{\tilde{\chi }}_1^{-}/\overline{t}b{\tilde{\chi }}_1^{+}.$

    

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5. Production of $$ {\textrm{K}}_{\textrm{S}}^0 $$ , Λ ($$ \overline{\Lambda} $$), Ξ±, and Ω± in jets and in the underlying event in pp and p–Pb collisions

   https://doi.org/10.1007/JHEP07(2023)136  

   Acharya, S. ; Adamová, D. ; Adler, A. ; Aglieri Rinella, G. ; Agnello, M. ; Agrawal, N. ; Ahammed, Z. ; Ahmad, S. ; Ahn, S. U. ; Ahuja, I. ; et al ( July 2023 , Journal of High Energy Physics)

   The production of strange hadrons ($$ {\textrm{K}}_{\textrm{S}}^0 $$$K_S^0$, Λ, Ξ^±, and Ω^±), baryon-to-meson ratios (Λ/$$ {\textrm{K}}_{\textrm{S}}^0 $$$K_S^0$, Ξ/$$ {\textrm{K}}_{\textrm{S}}^0 $$$K_S^0$, and Ω/$$ {\textrm{K}}_{\textrm{S}}^0 $$$K_S^0$), and baryon-to-baryon ratios (Ξ/Λ, Ω/Λ, and Ω/Ξ) associated with jets and the underlying event were measured as a function of transverse momentum (p_T) in pp collisions at$$ \sqrt{s} $$$\sqrt{s}$= 13 TeV and p Pb collisions at$$ \sqrt{s_{\textrm{NN}}} $$$\sqrt{s_{\mathrm{NN}}}$= 5.02 TeV with the ALICE detector at the LHC. The inclusive production of the same particle species and the corresponding ratios are also reported. The production of multi-strange hadrons, Ξ^±and Ω^±, and their associated particle ratios in jets and in the underlying event are measured for the first time. In both pp and p–Pb collisions, the baryon-to-meson and baryon-to-baryon yield ratios measured in jets differ from the inclusive particle production for low and intermediate hadronp_T(0.6–6 GeV/c). Ratios measured in the underlying event are in turn similar to those measured for inclusive particle production. In pp collisions, the particle production in jets is compared with Pythia8 predictions with three colour-reconnection implementation modes. None of them fully reproduces the data in the measured hadronp_Tregion. The maximum deviation is observed for Ξ^±and Ω^±which reaches a factor of about six. The event multiplicity dependence is further investigated in p−Pb collisions. In contrast to what is observed in the underlying event, there is no significant event-multiplicity dependence for particle production in jets. The presented measurements provide novel constraints on hadronisation and its Monte Carlo description. In particular, they demonstrate that the fragmentation of jets alone is insufficient to describe the strange and multi-strange particle production in hadronic collisions at LHC energies.

    

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