Search for a scalar partner of the top quark in the all-hadronic $t\bar{t}$ plus missing transverse momentum final state at $\sqrt{s}=13$ TeV with the ATLAS detector

Abstract

A search for direct pair production of scalar partners of the top quark (top squarks or scalar third-generation up-type leptoquarks) in the all-hadronic $t\bar{t}$ plus missing transverse momentum final state is presented. The analysis of 139 fb${}^{-1}$ of $\sqrt{s}=13$ TeV proton-proton collision data collected using the ATLAS detector at the LHC yields no significant excess over the Standard Model background expectation. To interpret the results, a supersymmetric model is used where the top squark decays via $\tilde{t}\to t^{(\ast )}{\tilde{\chi }}_1^0$, with $t^{(\ast )}$ denoting an on-shell (off-shell) top quark and ${\tilde{\chi }}_1^0$ the lightest neutralino. Three specific event selections are optimised for the following scenarios. In the scenario where $m_{\tilde{t}}>m_t+m_{{\tilde{\chi }}_1^0}$, top squark masses are excluded in the range 400-1250 GeV for ${\tilde{\chi }}_1^0$ masses below $200$ GeV at 95 % confidence level. In the situation where $m_{\tilde{t}}\sim m_t+m_{{\tilde{\chi }}_1^0}$, top squark masses in the range 300-630 GeV are excluded, while in the case where $m_{\tilde{t}}<m_W+m_b+m_{{\tilde{\chi }}_1^0}$ (with $m_{\tilde{t}}-m_{{\tilde{\chi }}_1^0}\ge 5$ GeV), considered for the first time in an ATLAS all-hadronic search, top squark masses in the range 300-660 GeV are excluded. Limits are also set for scalar third-generation up-type leptoquarks, excluding leptoquarks with masses below $1240$ GeV when considering only leptoquark decays into a top quark and a neutrino.

65 pages in total, author list starting page 49, 14 figures, 14 tables. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/SUSY-2018-12/

References in corpus (20)

• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• An Introduction to PYTHIA 8.2
• Event generation with SHERPA 1.1
• Vector boson production at hadron colliders: a fully exclusive QCD calculation at NNLO
• Two-loop soft anomalous dimensions for single top quark associated production with a W- or H-
• Single-top hadroproduction in association with a W boson
• Next-to-next-to-leading-order collinear and soft gluon corrections for t-channel single top quark production
• NNLL resummation for s-channel single top quark production
• The Tevatron at the Frontier of Dark Matter Direct Detection
• Threshold resummation for squark-antisquark and gluino-pair production at the LHC
• Simplified Models for a First Characterization of New Physics at the LHC
• Soft gluon resummation for the production of gluino-gluino and squark-antisquark pairs at the LHC
• Squark and gluino production cross sections in pp collisions at $\sqrt{s}$ = 13, 14, 33 and 100 TeV
• HistFitter software framework for statistical data analysis
• QCD NLO and EW NLO corrections to $t\bar{t}H$ production with top quark decays at hadron collider
• Searching for Directly Decaying Gluinos at the Tevatron
• NNLL-fast: predictions for coloured supersymmetric particle production at the LHC with threshold and Coulomb resummation
• NNLL resummation for squark and gluino production at the LHC
• Search for direct top squark pair production in events with one lepton, jets, and missing transverse momentum at 13 TeV with the CMS experiment
• Sparticles in Motion - getting to the line in compressed scenarios with the Recursive Jigsaw Reconstruction

Cited by in corpus (47)

• On the single leptoquark solutions to the $B$-physics anomalies
• Reading the footprints of the B-meson flavor anomalies
• Combination of searches for invisible decays of the Higgs boson using 139 fb${}^{-1}$ of proton-proton collision data at $\sqrt{s}=13$ TeV collected with the ATLAS experiment
• Search for dark matter produced in association with a leptonically decaying Z boson in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Searching for Leptoquarks at Future Muon Colliders
• Search for top squark production in fully-hadronic final states in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Search for new phenomena in events with two opposite-charge leptons, jets and missing transverse momentum in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Search for electroweak production of charginos and neutralinos in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Search for top squark pair production using dilepton final states in pp collision data collected at $\sqrt{s}=$ 13 TeV
• Combined searches for the production of supersymmetric top quark partners in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Search for electroweak production of charginos and neutralinos at $\sqrt{s}$ = 13 TeV in final states containing hadronic decays of WW, WZ, or WH and missing transverse momentum
• Dark Higgs Bosons at Colliders
• Higgsino Dark Matter in the MSSM
• Exploration at the high-energy frontier: ATLAS Run~2 searches investigating the exotic jungle beyond the Standard Model
• Search for new phenomena in $pp$ collisions in final states with tau leptons, $b$-jets, and missing transverse momentum with the ATLAS detector
• The quest to discover supersymmetry at the ATLAS experiment
• SModelS v2.3: enabling global likelihood analyses
• Observation of electroweak production of two jets in association with an isolated photon and missing transverse momentum, and search for a Higgs boson decaying into invisible particles at 13 TeV with the ATLAS detector
• Scalar leptoquark pair production at the LHC: precision predictions in the era of flavour anomalies
• Constraints on spin-0 dark matter mediators and invisible Higgs decays using ATLAS 13 TeV $pp$ collision data with two top quarks and missing transverse momentum in the final state
• Search for pair production of third-generation leptoquarks decaying into a bottom quark and a $\tau$-lepton with the ATLAS detector
• Status of searches for electroweak-scale supersymmetry after LHC Run 2
• New Physics Search at the CEPC: a General Perspective
• Precise probing and discrimination of third-generation scalar leptoquarks
• Loop induced top quark FCNC through top quark and dark matter interactions
• The Muon Magnetic Moment and Physics Beyond the Standard Model
• Combination of searches for pair-produced leptoquarks at $\sqrt{s}=13$ TeV with the ATLAS detector
• Search for dark matter produced in association with a single top quark and an energetic $W$ boson in $\sqrt{s}=$ 13 TeV $pp$ collisions with the ATLAS detector
• Probing bino NLSP at lepton colliders
• Dark Matter Freeze-In with a Heavy Mediator: Beyond the EFT Approach
• Probing mild-tempered neutralino dark matter through top-squark production at the LHC
• Spinning No-Scale $\mathcal{F}$-$SU$(5) in the Right Direction
• The Hierarchy Problem and the Top Yukawa: An Alternative to Top Partner Solutions
• NNLL-fast 2.0: Coloured Sparticle Production at the LHC Run 3 with $\sqrt{S}$ = 13.6 TeV
• The Higgs Boson Mass as Fundamental Parameter of the Minimal Supersymmetric Standard Model
• Search for leptoquark pair production decaying into $t{e}^{-}\bar{t}{e}^{+}$ or $t{\mu }^{-}\bar{t}{\mu }^{+}$ in multi-lepton final states in $pp$ collisions at 13 TeV with the ATLAS detector
• LHC Run-3, $b-\tau$ Yukawa Unification and Dark Matter Implications in SUSY 4-2-2 model
• MSSM at future Higgs factories
• Collider fingerprints of freeze-in dark matter produced during the fast expansion phase of Universe
• Dark Matter EFT, the Third -- Neutrino WIMPs
• Exploring Uncharted Soft Displaced Vertices in Open Data
• General search for supersymmetric particles in scenarios with compressed mass spectra using proton-proton collisions at $\sqrt{s}$ = 13 TeV
• The Right-Handed Slepton Bulk Region for Dark Matter in Generalized No-scale $\mathcal{F}$-$SU(5)$ with Effective Super-Natural Supersymmetry
• Markov Chain Monte Carlo analysis to probe trilinear $R$-parity violating SUSY scenarios and possible LHC signatures
• Triplet fermion WIMP dark matter in the general supersymmetric Georgi-Machacek model
• Implementation of full and simplified likelihoods in CheckMATE
• Searching for stop LSP at the LHC