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Search for a new scalar resonance in flavour-changing neutral-current top-quark decays t → qX (q = u, c), with X → b¯b, in proton-proton collisions at √s = 13 TeV with the ATLAS detector ATLAS Collaboration

Abstract

A search for flavour-changing neutral-current decays of a top quark into an up-type quark (either up or charm) and a light scalar particle X decaying into a bottom anti-bottom quark pair is presented. The search focuses on top-quark pair production where one top quark decays to qX, with X → b ¯b, and the other top quark decays according to the Standard Model, with the W boson decaying leptonically. The final state is thus characterised by an isolated electron or muon and at least four jets. Events are categorised according to the multiplicity of jets and jets tagged as originating from b-quarks, and a neural network is used to discriminate between signal and background processes. The data analysed correspond to 139 fb−1 of proton–proton collisions at a centre-of-mass energy of 13 TeV, recorded with the ATLAS detector at the LHC. The 95% confidence-level upper limits between 0.019% and 0.062% are derived for the branching fraction B(t → uX) and between 0.018% and 0.078% for the branching fraction B(t → cX), for masses of the scalar particle X between 20 and 160 GeV.

Item Metadata

Title
Search for a new scalar resonance in flavour-changing neutral-current top-quark decays t → qX (q = u, c), with X → b¯b, in proton-proton collisions at √s = 13 TeV with the ATLAS detector
Creator
ATLAS Collaboration
Publisher
Springer Berlin Heidelberg
Date Issued
2023-07-26
Description
A search for flavour-changing neutral-current decays of a top quark into an up-type quark (either up or charm) and a light scalar particle X decaying into a bottom anti-bottom quark pair is presented. The search focuses on top-quark pair production where one top quark decays to qX, with X → b ¯b, and the other top quark decays according to the Standard Model, with the W boson decaying leptonically. The final state is thus characterised by an isolated electron or muon and at least four jets. Events are categorised according to the multiplicity of jets and jets tagged as originating from b-quarks, and a neural network is used to discriminate between signal and background processes. The data analysed correspond to 139 fb−1 of proton–proton collisions at a centre-of-mass energy of 13 TeV, recorded with the ATLAS detector at the LHC. The 95% confidence-level upper limits between 0.019% and 0.062% are derived for the branching fraction B(t → uX) and between 0.018% and 0.078% for the branching fraction B(t → cX), for masses of the scalar particle X between 20 and 160 GeV.
Subject
Hadron-Hadron Scattering
Genre
Article
Type
Text
Language
eng
Date Available
2023-09-18
Provider
Vancouver : University of British Columbia Library
Rights
Attribution 4.0 International (CC BY 4.0)
DOI
10.14288/1.0435918
URI
http://hdl.handle.net/2429/85962
Affiliation
Science, Faculty of; TRIUMF; Non UBC; Physics and Astronomy, Department of
Citation
Journal of High Energy Physics. 2023 Jul 26;2023(7):199
Publisher DOI
10.1007/JHEP07(2023)199
Peer Review Status
Reviewed
Scholarly Level
Faculty; Researcher
Copyright Holder
The Author(s)
Rights URI
http://creativecommons.org/licenses/by/4.0/
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Attribution 4.0 International (CC BY 4.0)