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- Aad, G, et al.
(författare)
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Search for charged-lepton-flavor violating Formula Presented interactions in top-quark production and decay in Formula Presented collisions at Formula Presented with the ATLAS detector at the LHC
- 2024
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Ingår i: Physical Review D. - : American Physical Society (APS). - 2470-0010 .- 2470-0029. ; 110:1
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Tidskriftsartikel (refereegranskat)abstract
- A search for charged-lepton-flavor violating Formula Presented (Formula Presented, Formula Presented) interactions is presented, considering both top-quark production and decay. The data analyzed correspond to Formula Presented of proton-proton collisions at a center-of-mass energy of Formula Presented recorded with the ATLAS detector at the Large Hadron Collider. The analysis targets events containing two muons with the same electric charge, a hadronically decaying Formula Presented-lepton and at least one jet, with exactly one Formula Presented-tagged jet, produced by a Formula Presented interaction. Agreement with the Standard Model expectation within 1.6 standard deviations is observed, and limits are set at the 95% confidence level (CL) on the charged-lepton-flavor violation branching ratio of Formula Presented. An effective field theory interpretation is performed yielding 95% CL limits on Wilson coefficients, dependent on the flavor of the associated light quark and the Lorentz structure of the coupling. These range from Formula Presented for Formula Presented to Formula Presented for Formula Presented. An additional interpretation is performed for scalar leptoquark production inducing charged-lepton-flavor violation, with fixed intergenerational couplings. Upper limits on leptoquark coupling strengths are set at the 95% CL, ranging from Formula Presented to Formula Presented for leptoquark masses between 0.5 and 2.0 TeV. © 2024 CERN, for the ATLAS Collaboration.
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- Aad, G., et al.
(författare)
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Search for flavour-changing neutral-current couplings between the top quark and the Higgs boson in multi-lepton final states in 13 TeV pp collisions with the ATLAS detector
- 2024
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Ingår i: European Physical Journal C. - 1434-6044. ; 84:7
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Tidskriftsartikel (refereegranskat)abstract
- A search is presented for flavour-changing neutral-current interactions involving the top quark, the Higgs boson and an up-type quark (q=u,c) with the ATLAS detector at the Large Hadron Collider. The analysis considers leptonic decays of the top quark along with Higgs boson decays into two W bosons, two Z bosons or a τ+τ- pair. It focuses on final states containing either two leptons (electrons or muons) of the same charge or three leptons. The considered processes are tt¯ and Ht production. For the tt¯ production, one top quark decays via t→Hq. The proton–proton collision data set analysed amounts to (140fb-1) at (s=13TeV). No significant excess beyond Standard Model expectations is observed and upper limits are set on the t→Hq branching ratios at 95 % confidence level, amounting to observed (expected) limits of B(t→Hu)
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- Aad, G., et al.
(författare)
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Search for Nearly Mass-Degenerate Higgsinos Using Low-Momentum Mildly Displaced Tracks in pp Collisions at sqrt[s]=13 TeV with the ATLAS Detector
- 2024
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Ingår i: Physical Review Letters. - : American Physical Society (APS). - 1079-7114 .- 0031-9007. ; 132:22
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Tidskriftsartikel (refereegranskat)abstract
- Higgsinos with masses near the electroweak scale can solve the hierarchy problem and provide a dark matter candidate, while detecting them at the LHC remains challenging if their mass splitting is O(1 GeV). This Letter presents a novel search for nearly mass-degenerate Higgsinos in events with an energetic jet, missing transverse momentum, and a low-momentum track with a significant transverse impact parameter using 140 fb^{-1} of proton-proton collision data at sqrt[s]=13 TeV collected by the ATLAS experiment. For the first time since LEP, a range of mass splittings between the lightest charged and neutral Higgsinos from 0.3 to 0.9 GeV is excluded at 95% confidence level, with a maximum reach of approximately 170 GeV in the Higgsino mass.
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- Aad, G., et al.
(författare)
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Searches for exclusive Higgs boson decays into D⁎γ and Z boson decays into D0γ and Ks0γ in pp collisions at s=13TeV with the ATLAS detector
- 2024
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 855
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Tidskriftsartikel (refereegranskat)abstract
- Searches for exclusive decays of the Higgs boson into D⁎γ and of the Z boson into D0γ and Ks0γ can probe flavour-violating Higgs boson and Z boson couplings to light quarks. Searches for these decays are performed with a pp collision data sample corresponding to an integrated luminosity of 136.3 fb−1 collected at s=13TeV between 2016–2018 with the ATLAS detector at the CERN Large Hadron Collider. In the D⁎γ and D0γ channels, the observed (expected) 95% confidence-level upper limits on the respective branching fractions are B(H→D⁎γ)
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