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1. Inclusive and differential cross section measurements of $$ \textrm{t}\overline{\textrm{t}}\textrm{b}\overline{\textrm{b}} $$ production in the lepton+jets channel at $$ \sqrt{s} $$ = 13 TeV

   https://doi.org/10.1007/JHEP05(2024)042  

   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 (May 2024, Journal of High Energy Physics)

   A<sc>bstract</sc> Measurements of inclusive and normalized differential cross sections of the associated production of top quark-antiquark and bottom quark-antiquark pairs,$$ \textrm{t}\overline{\textrm{t}}\textrm{b}\overline{\textrm{b}} $$ $t\overline{t}b\overline{b}$, are presented. The results are based on data from proton-proton collisions collected by the CMS detector at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb⁻¹. The cross sections are measured in the lepton+jets decay channel of the top quark pair, using events containing exactly one isolated electron or muon and at least five jets. Measurements are made in four fiducial phase space regions, targeting different aspects of the$$ \textrm{t}\overline{\textrm{t}}\textrm{b}\overline{\textrm{b}} $$ $t\overline{t}b\overline{b}$process. Distributions are unfolded to the particle level through maximum likelihood fits, and compared with predictions from several event generators. The inclusive cross section measurements of this process in the fiducial phase space regions are the most precise to date. In most cases, the measured inclusive cross sections exceed the predictions with the chosen generator settings. The only exception is when using a particular choice of dynamic renormalization scale,$$ {\mu}_{\textrm{R}}=\frac{1}{2}{\prod}_{i=\textrm{t},\overline{\textrm{t}},\textrm{b},\overline{\textrm{b}}}{m}_{\textrm{T},i}^{1/4} $$ ${\mu }_R=\frac{1}{2}{\prod }_{i=t,\overline{t},b,\overline{b}}{m}_{T,i}^{1/4}$, where$$ {m}_{\textrm{T},i}^2={m}_i^2+{p}_{\textrm{T},i}^2 $$ $m_{T,i}^2=m_i^2+p_{T,i}^2$are the transverse masses of top and bottom quarks. The differential cross sections show varying degrees of compatibility with the theoretical predictions, and none of the tested generators with the chosen settings simultaneously describe all the measured distributions. 

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2. Measurement of the $$ \textrm{t}\overline{\textrm{t}}\textrm{H} $$ and tH production rates in the H → $$ \textrm{b}\overline{\textrm{b}} $$ decay channel using proton-proton collision data at $$ \sqrt{s} $$ = 13 TeV

   https://doi.org/10.1007/JHEP02(2025)097  

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

   A<sc>bstract</sc> An analysis of the production of a Higgs boson (H) in association with a top quark-antiquark pair ($$ \textrm{t}\overline{\textrm{t}}\textrm{H} $$ $t\overline{t}H$) or a single top quark (tH) is presented. The Higgs boson decay into a bottom quark-antiquark pair (H →$$ \textrm{b}\overline{\textrm{b}} $$ $b\overline{b}$) is targeted, and three different final states of the top quark decays are considered, defined by the number of leptons (electrons or muons) in the event. The analysis utilises proton-proton collision data collected at the CERN LHC with the CMS experiment at$$ \sqrt{s} $$ $\sqrt{s}$= 13 TeV in 2016–2018, which correspond to an integrated luminosity of 138 fb⁻¹. The observed$$ \textrm{t}\overline{\textrm{t}}\textrm{H} $$ $t\overline{t}H$production rate relative to the standard model expectation is 0.33 ± 0.26 = 0.33 ± 0.17(stat) ± 0.21(syst). Additionally, the$$ \textrm{t}\overline{\textrm{t}}\textrm{H} $$ $t\overline{t}H$production rate is determined in intervals of Higgs boson transverse momentum. An upper limit at 95% confidence level is set on the tH production rate of 14.6 times the standard model prediction, with an expectation of$$ {19.3}_{-6.0}^{+9.2} $$ ${19.3}_{-6.0}^{+9.2}$. Finally, constraints are derived on the strength and structure of the coupling between the Higgs boson and the top quark from simultaneous extraction of the$$ \textrm{t}\overline{\textrm{t}}\textrm{H} $$ $t\overline{t}H$and tH production rates, and the results are combined with those obtained in other Higgs boson decay channels. 

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3. 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<sc>bstract</sc> 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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4. Measurement of the inclusive $$ \textrm{t}\overline{\textrm{t}} $$ cross section in final states with at least one lepton and additional jets with 302 pb−1 of pp collisions at $$ \sqrt{\textrm{s}} $$ = 5.02 TeV

   https://doi.org/10.1007/JHEP04(2025)099  

   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> A measurement of the top quark pair ($$ \textrm{t}\overline{\textrm{t}} $$ $t\overline{t}$) production cross section in proton-proton collisions at a centre-of-mass energy of 5.02 TeV is presented. The data were collected at the LHC in autumn 2017, in dedicated runs with low-energy and low-intensity conditions with respect to the default configuration, and correspond to an integrated luminosity of 302 pb⁻¹. The measurement is performed using events with one electron or muon, and multiple jets, at least one of them being identified as originating from a b quark (b tagged). Events are classified based on the number of all reconstructed jets and of b-tagged jets. Multivariate analysis techniques are used to enhance the separation between the signal and backgrounds. The measured cross section is$$ 62.5\pm 1.6{\left(\textrm{stat}\right)}_{-2.5}^{+2.6}\left(\textrm{syst}\right)\pm 1.2\left(\textrm{lumi}\right) $$ $62.5\pm 1.6{\left(\text{stat}\right)}_{-2.5}^{+2.6}\left(\text{syst}\right)\pm 1.2\left(\text{lumi}\right)$pb. A combination with the result in the dilepton channel based on the same data set yields a value of 62.3 ± 1.5 (stat) ± 2.4 (syst) ± 1.2 (lumi) pb, to be compared with the standard model prediction of$$ {69.5}_{-3.7}^{+3.5} $$ ${69.5}_{-3.7}^{+3.5}$pb at next-to-next-to-leading order in perturbative quantum chromodynamics. 

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5. Constraining the $${\overline{\textrm{K}}}{\textrm{N}}$$ coupled channel dynamics using femtoscopic correlations at the LHC

   https://doi.org/10.1140/epjc/s10052-023-11476-0  

   Acharya, S.; Adamová, D.; Adler, A.; Aglieri Rinella, G.; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahmad, S.; Ahn, S. U.; Ahuja, I.; et al (April 2023, The European Physical Journal C)

   Abstract The interaction of $$\textrm{K}^{-}$$ K - with protons is characterised by the presence of several coupled channels, systems like $${\overline{\textrm{K}}}^0$$ K ¯ 0 n and $$\uppi \Sigma $$ π Σ with a similar mass and the same quantum numbers as the $$\textrm{K}^{-}$$ K - p state. The strengths of these couplings to the $$\textrm{K}^{-}$$ K - p system are of crucial importance for the understanding of the nature of the $$\Lambda (1405)$$ Λ ( 1405 ) resonance and of the attractive $$\textrm{K}^{-}$$ K - p strong interaction. In this article, we present measurements of the $$\textrm{K}^{-}$$ K - p correlation functions in relative momentum space obtained in pp collisions at $$\sqrt{s}~=~13$$ s = 13  Te, in p–Pb collisions at $$\sqrt{s_{\textrm{NN}}}~=~5.02$$ s NN = 5.02  Te, and (semi)peripheral Pb–Pb collisions at $$\sqrt{s_{\textrm{NN}}}~=~5.02$$ s NN = 5.02  Te. The emitting source size, composed of a core radius anchored to the $$\textrm{K}^{+}$$ K + p correlation and of a resonance halo specific to each particle pair, varies between 1 and 2 fm in these collision systems. The strength and the effects of the $${\overline{\textrm{K}}}^0$$ K ¯ 0 n and $$\uppi \Sigma $$ π Σ inelastic channels on the measured $$\textrm{K}^{-}$$ K - p correlation function are investigated in the different colliding systems by comparing the data with state-of-the-art models of chiral potentials. A novel approach to determine the conversion weights $$\omega $$ ω , necessary to quantify the amount of produced inelastic channels in the correlation function, is presented. In this method, particle yields are estimated from thermal model predictions, and their kinematic distribution from blast-wave fits to measured data. The comparison of chiral potentials to the measured $$\textrm{K}^{-}$$ K - p interaction indicates that, while the $$\uppi \Sigma $$ π Σ – $$\textrm{K}^{-}$$ K - p dynamics is well reproduced by the model, the coupling to the $${\overline{\textrm{K}}}^0$$ K ¯ 0 n channel in the model is currently underestimated. 

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