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  3. A search for the nonresonant production of Higgs boson pairs in theHHbb¯τ+τchannel is performed using140fb1of proton-proton collisions at a center-of-mass energy of 13 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. The analysis strategy is optimized to probe anomalous values of the Higgs boson self-coupling modifierκλand of the quarticHHVV(V=W,Z) coupling modifierκ2V. No significant excess above the expected background from Standard Model processes is observed. An observed (expected) upper limitμHH<5.9(3.3)is set at 95% confidence-level on the Higgs boson pair production cross section normalized to its Standard Model prediction. The coupling modifiers are constrained to an observed (expected) 95% confidence interval of3.1<κλ<9.0(2.5<κλ<9.3) and0.5<κ2V<2.7(0.2<κ2V<2.4), assuming all other Higgs boson couplings are fixed to the Standard Model prediction. The results are also interpreted in the context of effective field theories via constraints on anomalous Higgs boson couplings and Higgs boson pair production cross sections assuming different kinematic benchmark scenarios.

    © 2024 CERN, for the ATLAS Collaboration2024CERN 
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  4. Abstract

    A search for leptoquark pair production decaying into$$te^- \bar{t}e^+$$te-t¯e+or$$t\mu ^- \bar{t}\mu ^+$$tμ-t¯μ+in final states with multiple leptons is presented. The search is based on a dataset ofppcollisions at$$\sqrt{s}=13~\text {TeV} $$s=13TeVrecorded with the ATLAS detector during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb$$^{-1}$$-1. Four signal regions, with the requirement of at least three light leptons (electron or muon) and at least two jets out of which at least one jet is identified as coming from ab-hadron, are considered based on the number of leptons of a given flavour. The main background processes are estimated using dedicated control regions in a simultaneous fit with the signal regions to data. No excess above the Standard Model background prediction is observed and 95% confidence level limits on the production cross section times branching ratio are derived as a function of the leptoquark mass. Under the assumption of exclusive decays into$$te^{-}$$te-($$t\mu ^{-}$$tμ-), the corresponding lower limit on the scalar mixed-generation leptoquark mass$$m_{\textrm{LQ}_{\textrm{mix}}^{\textrm{d}}}$$mLQmixdis at 1.58 (1.59) TeV and on the vector leptoquark mass$$m_{{\tilde{U}}_1}$$mU~1at 1.67 (1.67) TeV in the minimal coupling scenario and at 1.95 (1.95) TeV in the Yang–Mills scenario.

     
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  5. Abstract

    The ATLAS trigger system is a crucial component of the ATLAS experiment at the LHC. It is responsible for selecting events in line with the ATLAS physics programme. This paper presents an overview of the changes to the trigger and data acquisition system during the second long shutdown of the LHC, and shows the performance of the trigger system and its components in the proton-proton collisions during the 2022 commissioning period as well as its expected performance in proton-proton and heavy-ion collisions for the remainder of the third LHC data-taking period (2022–2025).

     
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    Free, publicly-accessible full text available June 1, 2025
  6. A search for high-mass resonances decaying into aτ-lepton and a neutrino using proton-proton collisions at a center-of-mass energy ofs=13TeVis presented. The full run 2 data sample corresponding to an integrated luminosity of139fb1recorded by the ATLAS experiment in the years 2015–2018 is analyzed. Theτ-lepton is reconstructed in its hadronic decay modes and the total transverse momentum carried out by neutrinos is inferred from the reconstructed missing transverse momentum. The search for new physics is performed on the transverse mass between theτ-lepton and the missing transverse momentum. No excess of events above the Standard Model expectation is observed and upper exclusion limits are set on theWτνproduction cross section. HeavyWvector bosons with masses up to 5.0 TeV are excluded at 95% confidence level, assuming that they have the same couplings as the Standard ModelWboson. For nonuniversal couplings,Wbosons are excluded for masses less than 3.5–5.0 TeV, depending on the model parameters. In addition, model-independent limits on the visible cross section times branching ratio are determined as a function of the lower threshold on the transverse mass of theτ-lepton and missing transverse momentum.

    <supplementary-material><permissions><copyright-statement>© 2024 CERN, for the ATLAS Collaboration</copyright-statement><copyright-year>2024</copyright-year><copyright-holder>CERN</copyright-holder></permissions></supplementary-material></sec> </div> <a href='#' class='show open-abstract' style='margin-left:10px;'>more »</a> <a href='#' class='hide close-abstract' style='margin-left:10px;'>« less</a> <div class="actions" style="padding-left:10px;"> <span class="reader-count"> Free, publicly-accessible full text available June 1, 2025</span> </div> </div><div class="clearfix"></div> </div> </li> <li> <div class="article item document" itemscope itemtype="http://schema.org/TechArticle"> <div class="item-info"> <div class="title"> <a href="https://par.nsf.gov/biblio/10534033-search-pair-production-higgsinos-events-two-higgs-bosons-missing-transverse-momentum-pp-collisions-atlas-experiment" itemprop="url"> <span class='span-link' itemprop="name">Search for pair production of higgsinos in events with two Higgs bosons and missing transverse momentum in s=13  TeV pp collisions at the ATLAS experiment</span> </a> </div> <div> <strong> <a class="misc external-link" href="https://doi.org/10.1103/PhysRevD.109.112011" target="_blank" title="Link to document DOI">https://doi.org/10.1103/PhysRevD.109.112011  <span class="fas fa-external-link-alt"></span></a> </strong> </div> <div class="metadata"> <span class="authors"> <span class="author" itemprop="author">Aad, G</span> <span class="sep">; </span><span class="author" itemprop="author">Abbott, B</span> <span class="sep">; </span><span class="author" itemprop="author">Abeling, K</span> <span class="sep">; </span><span class="author" itemprop="author">Abicht, N J</span> <span class="sep">; </span><span class="author" itemprop="author">Abidi, S H</span> <span class="sep">; </span><span class="author" itemprop="author">Aboulhorma, A</span> <span class="sep">; </span><span class="author" itemprop="author">Abramowicz, H</span> <span class="sep">; </span><span class="author" itemprop="author">Abreu, H</span> <span class="sep">; </span><span class="author" itemprop="author">Abulaiti, Y</span> <span class="sep">; </span><span class="author" itemprop="author">Acharya, B S</span> <span class="sep">; </span><span class="author">et al</span></span> <span class="year">( <time itemprop="datePublished" datetime="2024-06-01">June 2024</time> , Physical Review D) </span> </div> <div style="cursor: pointer;-webkit-line-clamp: 5;" class="abstract" itemprop="description"> <p>This paper presents a search for pair production of higgsinos, the supersymmetric partners of the Higgs bosons, in scenarios with gauge-mediated supersymmetry breaking. Each higgsino is assumed to decay into a Higgs boson and a nearly massless gravitino. The search targets events where each Higgs boson decays into<math display='inline'><mi>b</mi><mover accent='true'><mi>b</mi><mo stretchy='false'>¯</mo></mover></math>, leading to a reconstructed final state with at least three energetic<math display='inline'><mi>b</mi></math>-jets and missing transverse momentum. Two complementary analysis channels are used, with each channel specifically targeting either low or high values of the higgsino mass. The low-mass (high-mass) channel exploits<math display='inline'><mrow><mn>126</mn><mtext> </mtext><mo stretchy='false'>(</mo><mn>139</mn><mo stretchy='false'>)</mo><mtext> </mtext><mtext> </mtext><msup><mrow><mi>fb</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math>of<math display='inline'><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>13</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></math>data collected by the ATLAS detector during Run 2 of the Large Hadron Collider. No significant excess above the Standard Model prediction is found. At 95% confidence level, masses between 130 GeV and 940 GeV are excluded for higgsinos decaying exclusively into Higgs bosons and gravitinos. Exclusion limits as a function of the higgsino decay branching ratio to a Higgs boson are also reported.</p> <sec><supplementary-material><permissions><copyright-statement>© 2024 CERN, for the ATLAS Collaboration</copyright-statement><copyright-year>2024</copyright-year><copyright-holder>CERN</copyright-holder></permissions></supplementary-material></sec> </div> <a href='#' class='show open-abstract' style='margin-left:10px;'>more »</a> <a href='#' class='hide close-abstract' style='margin-left:10px;'>« less</a> <div class="actions" style="padding-left:10px;"> <span class="reader-count"> Free, publicly-accessible full text available June 1, 2025</span> </div> </div><div class="clearfix"></div> </div> </li> </ol> <div id="pagination-lower" style=""> <div class="pull-right" style="line-height: 30px;"> <div class="btn-group pagination nomargin"> <a href="#" class="btn btn-sm btn-default noborderradius" disabled="disabled">«<span class="hidden-xs"> Prev</span></a> <a class="dropdown-toggle btn btn-sm btn-default paging-dropdown hidden-xs noborderradius" href="#" data-toggle="dropdown"><span class="caret"></span><span class="sr-only">Select page number</span></a> <div class="dropdown-menu pull-right paging-slider-dropdown" style="padding: 15px;"> <small> <div class="text-muted" style="line-height:20px;"><label for="pagination-sel-sptag-2">Go to page: <span class="paging-target">1</span> of <span class="paging-max">39</span></label></div> <div> <table> <tr> <td valign="top"> <input id="pagination-sel-sptag-2" data-range="" value="1" min="1" max="39" name="pagination-sel" type="range" class="pagination-sel noborderradius" style="height:26px;padding:0px;margin-right:5px; 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