Search for a scalar partner of the top quark in the all-hadronic tt¯ plus missing transverse momentum final state at √s=13 TeV with the ATLAS detector

G Aad, Torsten Åkesson, Simona Bocchetta, Eric Edward Corrigan, Caterina Doglioni, Jannik Geisen, Kristian Gregersen, Eva Brottmann Hansen, Vincent Hedberg, Göran Jarlskog, Edgar Kellermann, Balazs Konya, Else Lytken, Katja Mankinen, Caterina Marcon, Ulf Mjörnmark, Geoffrey André Adrien Mullier, Ruth Pöttgen, Trine Poulsen, Eleni SkordaOxana Smirnova, L. Zwalinski, ATLAS Collaboration

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskriftPeer review

Sammanfattning

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 tt¯ plus missing transverse momentum final state is presented. The analysis of 139 fb - 1 of 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 t~→t(∗)χ~10, with t(∗) denoting an on-shell (off-shell) top quark and χ~10 the lightest neutralino. Three specific event selections are optimised for the following scenarios. In the scenario where mt~>mt+mχ~10, top squark masses are excluded in the range 400–1250 GeV for χ~10 masses below 200 GeV at 95% confidence level. In the situation where mt~∼mt+mχ~10, top squark masses in the range 300–630 GeV are excluded, while in the case where mt~<mW+mb+mχ~10 (with mt~-mχ~10≥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. © 2020, CERN for the benefit of the ATLAS collaboration.
Originalspråkengelska
Artikelnummer737
TidskriftEuropean Physical Journal C
Volym80
Nummer8
DOI
StatusPublished - 2020

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