TY - JOUR
T1 - Search for a new scalar resonance in flavour-changing neutral-current top-quark decays t → qX (q = u, c), with X → bb¯ , in proton-proton collisions at √s = 13 TeV with the ATLAS detector
AU - Aad, G.
AU - Åkesson, T.P.A.
AU - Corrigan, E.E.
AU - Doglioni, C.
AU - Ekman, P.A.
AU - Geisen, J.
AU - Hedberg, V.
AU - Jarlskog, G.
AU - Konya, B.
AU - Lytken, E.
AU - Mjörnmark, J.U.
AU - Mullier, G.A.
AU - Poettgen, R.
AU - Simpson, N.D.
AU - Skorda, E.
AU - Smirnova, O.
AU - Zwalinski, L.
AU - ATLAS Collaboration
PY - 2023
Y1 - 2023
N2 - 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 → bb¯ , 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. [Figure not available: see fulltext.] © 2023, The Author(s).
AB - 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 → bb¯ , 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. [Figure not available: see fulltext.] © 2023, The Author(s).
KW - Hadron-Hadron Scattering
U2 - 10.1007/JHEP07(2023)199
DO - 10.1007/JHEP07(2023)199
M3 - Article
SN - 1029-8479
VL - 2023
JO - Journal of High Energy Physics
JF - Journal of High Energy Physics
IS - 7
M1 - 199
ER -