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1. Measurement of the mass dependence of the transverse momentum of lepton pairs in Drell–Yan production in proton–proton collisions at $$\sqrt{s} = 13\,\text {Te\hspace{-.08em}V} $$

   https://doi.org/10.1140/epjc/s10052-023-11631-7  

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

   The double differential cross sections of the Drell–Yan lepton pair ($$\ell ^+\ell ^-$$${\ell }^{+}{\ell }^{-}$, dielectron or dimuon) production are measured as functions of the invariant mass$$m_{\ell \ell }$$$m_{\ell \ell }$, transverse momentum$$p_{\textrm{T}} (\ell \ell )$$$p_{\text{T}}\left(\ell \ell \right)$, and$$\varphi ^{*}_{\eta }$$${\phi }_{\eta }^{\ast }$. The$$\varphi ^{*}_{\eta }$$${\phi }_{\eta }^{\ast }$observable, derived from angular measurements of the leptons and highly correlated with$$p_{\textrm{T}} (\ell \ell )$$$p_{\text{T}}\left(\ell \ell \right)$, is used to probe the low-$$p_{\textrm{T}} (\ell \ell )$$$p_{\text{T}}\left(\ell \ell \right)$region in a complementary way. Dilepton masses up to 1$$\,\text {Te\hspace{-.08em}V}$$$\text{Te}\text{V}$are investigated. Additionally, a measurement is performed requiring at least one jet in the final state. To benefit from partial cancellation of the systematic uncertainty, the ratios of the differential cross sections for various$$m_{\ell \ell }$$$m_{\ell \ell }$ranges to those in the Z mass peak interval are presented. The collected data correspond to an integrated luminosity of 36.3$$\,\text {fb}^{-1}$$${\text{fb}}^{-1}$of proton–proton collisions recorded with the CMS detector at the LHC at a centre-of-mass energy of 13$$\,\text {Te\hspace{-.08em}V}$$$\text{Te}\text{V}$. Measurements are compared with predictions based on perturbative quantum chromodynamics, including soft-gluon resummation.

    

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2. On the sensitivity reach of $$\textrm{LQ}$$ production with preferential couplings to third generation fermions at the LHC

   https://doi.org/10.1140/epjc/s10052-023-12177-4  

   Flórez, A. ; Jones-Pérez, J. ; Gurrola, A. ; Rodriguez, C. ; Peñuela-Parra, J. ( November 2023 , The European Physical Journal C)

   Leptoquarks ($$\textrm{LQ}$$$\text{LQ}$s) are hypothetical particles that appear in various extensions of the Standard Model (SM), that can explain observed differences between SM theory predictions and experimental results. The production of these particles has been widely studied at various experiments, most recently at the Large Hadron Collider (LHC), and stringent bounds have been placed on their masses and couplings, assuming the simplest beyond-SM (BSM) hypotheses. However, the limits are significantly weaker for$$\textrm{LQ}$$$\text{LQ}$models with family non-universal couplings containing enhanced couplings to third-generation fermions. We present a new study on the production of a$$\textrm{LQ}$$$\text{LQ}$at the LHC, with preferential couplings to third-generation fermions, considering proton-proton collisions at$$\sqrt{s} = 13 \, \textrm{TeV}$$$\sqrt{s}=13\text{TeV}$and$$\sqrt{s} = 13.6 \, \textrm{TeV}$$$\sqrt{s}=13.6\text{TeV}$. Such a hypothesis is well motivated theoretically and it can explain the recent anomalies in the precision measurements of$$\textrm{B}$$$\text{B}$-meson decay rates, specifically the$$R_{D^{(*)}}$$$R_{D^{(\ast )}}$ratios. Under a simplified model where the$$\textrm{LQ}$$$\text{LQ}$masses and couplings are free parameters, we focus on cases where the$$\textrm{LQ}$$$\text{LQ}$decays to a$$\tau $$$\tau$lepton and a$$\textrm{b}$$$\text{b}$quark, and study how the results are affected by different assumptions about chiral currents and interference effects with other BSM processes with the same final states, such as diagrams with a heavy vector boson,$$\textrm{Z}^{\prime }$$${\text{Z}}^{\prime }$. The analysis is performed using machine learning techniques, resulting in an increased discovery reach at the LHC, allowing us to probe new physics phase space which addresses the$$\textrm{B}$$$\text{B}$-meson anomalies, for$$\textrm{LQ}$$$\text{LQ}$masses up to$$5.00\, \textrm{TeV}$$$5.00\text{TeV}$, for the high luminosity LHC scenario.

    

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3. Search for supersymmetry in final states with a single electron or muon using angular correlations and heavy-object identification in proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV

   https://doi.org/10.1007/JHEP09(2023)149  

   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 ( September 2023 , Journal of High Energy Physics)

   A search for supersymmetry is presented in events with a single charged lepton, electron or muon, and multiple hadronic jets. The data correspond to an integrated luminosity of 138 fb⁻¹of proton-proton collisions at a center-of-mass energy of 13 TeV, recorded by the CMS experiment at the CERN LHC. The search targets gluino pair production, where the gluinos decay into final states with the lightest supersymmetric particle (LSP) and either a top quark-antiquark ($$ \textrm{t}\overline{\textrm{t}} $$$t\overline{t}$) pair, or a light-flavor quark-antiquark ($$ \textrm{q}\overline{\textrm{q}} $$$q\overline{q}$) pair and a virtual or on-shell W boson. The main backgrounds,$$ \textrm{t}\overline{\textrm{t}} $$$t\overline{t}$pair and W+jets production, are suppressed by requirements on the azimuthal angle between the momenta of the lepton and of its reconstructed parent W boson candidate, and by top quark and W boson identification based on a machine-learning technique. The number of observed events is consistent with the expectations from standard model processes. Limits are evaluated on supersymmetric particle masses in the context of two simplified models of gluino pair production. Exclusions for gluino masses reach up to 2120 (2050) GeV at 95% confidence level for a model with gluino decay to a$$ \textrm{t}\overline{\textrm{t}} $$$t\overline{t}$pair (a$$ \textrm{q}\overline{\textrm{q}} $$$q\overline{q}$pair and a W boson) and the LSP. For the same models, limits on the mass of the LSP reach up to 1250 (1070) GeV.

    

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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. Measurements of the associated production of a W boson and a charm quark in proton–proton collisions at $$\sqrt{s}=8\,\text {TeV} $$

   https://doi.org/10.1140/epjc/s10052-022-10897-7  

   Tumasyan, A. ; Adam, W. ; Bergauer, T. ; Dragicevic, M. ; Erö, J. ; Valle, A. Escalante ; Frühwirth, R. ; Jeitler, M. ; Krammer, N. ; Lechner, L. ; et al ( December 2022 , The European Physical Journal C)

   Measurements of the associated production of a W boson and a charm ($${\text {c}}$$$\text{c}$) quark in proton–proton collisions at a centre-of-mass energy of 8$$\,\text {TeV}$$$\text{TeV}$are reported. The analysis uses a data sample corresponding to a total integrated luminosity of 19.7$$\,\text {fb}^{-1}$$${\text{fb}}^{-1}$collected by the CMS detector at the LHC. The W bosons are identified through their leptonic decays to an electron or a muon, and a neutrino. Charm quark jets are selected using distinctive signatures of charm hadron decays. The product of the cross section and branching fraction$$\sigma (\text {p}\text {p}\rightarrow \text {W}+ {\text {c}}+ \text {X}) {\mathcal {B}}(\text {W}\rightarrow \ell \upnu )$$$\sigma (\text{pp}\to \text{W}+\text{c}+\text{X})B(\text{W}\to \ell \nu )$, where$$\ell = \text {e}$$$\ell =\text{e}$or$$\upmu $$$\mu$, and the cross section ratio$$\sigma (\text {p}\text {p}\rightarrow {{\text {W}}^{+} + \bar{{\text {c}}} + \text {X}}) / \sigma (\text {p}\text {p}\rightarrow {{\text {W}}^{-} + {\text {c}}+ \text {X}})$$$\sigma (\text{pp}\to {\text{W}}^{+}+\overline{\text{c}}+\text{X})/\sigma (\text{pp}\to {\text{W}}^{-}+\text{c}+\text{X})$are measured in a fiducial volume and differentially as functions of the pseudorapidity and of the transverse momentum of the lepton from the W boson decay. The results are compared with theoretical predictions. The impact of these measurements on the determination of the strange quark distribution is assessed.

    

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