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

ATLAS Collaboration

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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 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.

Original languageEnglish
Article number737
Pages (from-to)1-44
Number of pages44
JournalEuropean Physical Journal C
Volume80
Issue number8
DOIs
Publication statusPublished - Aug 2020
Externally publishedYes

Bibliographical note

Copyright the Author(s) 2020. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

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