CERN Accelerating science

Article
Report number arXiv:2401.13430 ; CERN-EP-2024-003
Title Search for new phenomena with top-quark pairs and large missing transverse momentum using 140 fb1 of pp collision data at s=13 TeV with the ATLAS detector
Author(s) ATLAS Collaboration  Mostrar todos os 2930 autores
Corporate Author(s) ATLAS Collaboration
Publication 2024-03-26
Imprint 25 Jan 2024
Number of pages 56
Note All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/SUSY-2023-22/
In: JHEP 2403 (2024) 139
DOI 10.1007/JHEP03(2024)139 (publication)
Subject category Particle Physics - Experiment
Accelerator/Facility, Experiment CERN LHC ; ATLAS
Free keywords supersymmetry ; particle and resonance production ; experimental results ; SUSY search ; tt + met
Abstract A search is conducted for new phenomena in events with a top quark pair and large missing transverse momentum, where the top quark pair is reconstructed in final states with one isolated electron or muon and multiple jets. The search is performed using the Large Hadron Collider proton-proton collision data sample at a centre-of-mass energy of s=13 TeV recorded by the ATLAS detector that corresponds to an integrated luminosity of 140 fb1. An analysis based on neural network classifiers is optimised to search for directly produced pairs of supersymmetric partners of the top quark (stop), and to search for spin-0 mediators, produced in association with a pair of top quarks, that decay into dark-matter particles. In the stop search, the analysis is designed to target models in which the mass difference between the stop and the neutralino from the stop decay is close to the top quark mass. This new analysis is combined with a previously published search in final states with no leptons to provide high sensitivity to models with larger mass differences. In the search for spin-0 mediators, the analysis is designed to target mediator masses lighter than twice the top quark mass and is combined with previously published searches in final states with zero or two leptons. No significant excess above the Standard Model background is observed, and limits at 95% confidence level are set. Models with neutralinos from direct stop decay with masses up to 570 GeV are excluded, while for small neutralino masses models are excluded for stop masses up to 1230 GeV. Scalar (pseudoscalar) dark matter mediator masses as large as 350 (370) GeV are excluded when the coupling strengths of the mediator to Standard Model and dark-matter particles are both set to one. At lower mediator masses, models with production cross-sections as small as 0.15 (0.16) times the nominal predictions are excluded. Results of this search are also used to set constraints on effective four-fermion contact interactions between top quarks and neutrinos.
Related document supersedes: ATLAS-CONF-2023-043
Copyright/License Preprint: © 2024-2025 CERN (License: CC-BY-4.0)
Publication: © 2024-2025 CERN (License: CC-BY-4.0), sponsored by SCOAP³



Corresponding record in: Inspire
Email contact: tatjana.lenz@cern.ch


 Record created 2024-01-25, last modified 2024-12-13


Fulltext:
2401.13430 - Download fulltextPDF
document - Download fulltextPDF
External link:
Download fulltextPrevious draft version
  • Send to ScienceWise.info