TY - JOUR
T1 - Search for flavour-changing neutral current top-quark decays t -> qZ in proton-proton collisions at root s=13 TeV with the ATLAS detector
AU - Aaboud, M.
AU - Aad, G.
AU - Abbott, B.
AU - Abdinov, O.
AU - Abeloos, B
AU - Abidi, S.H.
AU - Abouzeid, Ossama Sherif Alexander
AU - Abraham, NL
AU - Abramowicz, H.
AU - Abreu, H.
AU - Abulaiti, Y.
AU - Acharya, B.S.
AU - Adachi, Sosuke
AU - Adamczyk, L.
AU - Adelman, J.
AU - Adersberger, M.
AU - Adye, T.
AU - Affolder, A. A.
AU - Afik, Y.
AU - Agheorghiesei, C.
AU - Aguilar-Saavedra, J. A.
AU - Ahmadov, F.
AU - Alonso Diaz, Alejandro
AU - Besjes, Geert-Jan
AU - Bajic, Milena
AU - de Almeida Dias, Flavia
AU - Dam, Mogens
AU - Galster, Gorm Aske Gram Krohn
AU - Hansen, Jørn Dines
AU - Hansen, Jørgen Beck
AU - Hansen, Peter Henrik
AU - Monk, James William
AU - Petersen, Troels Christian
AU - Stark, Simon Holm
AU - Thiele, Fabian Alexander Jürgen
AU - Wiglesworth, Graig
AU - Xella, Stefania
PY - 2018/7/1
Y1 - 2018/7/1
N2 - A search for flavour-changing neutral-current processes in top-quark decays is presented. Data collected with the ATLAS detector from proton-proton collisions at the Large Hadron Collider at a centre-of-mass energy of s=13 TeV, corresponding to an integrated luminosity of 36.1 fb−1, are analysed. The search is performed using top-quark pair events, with one top quark decaying through the t → qZ (q = u, c) flavour-changing neutral-current channel, and the other through the dominant Standard Model mode t → bW. Only Z boson decays into charged leptons and leptonic W boson decays are considered as signal. Consequently, the final-state topology is characterized by the presence of three isolated charged leptons (electrons or muons), at least two jets, one of the jets originating from a b-quark, and missing transverse momentum from the undetected neutrino. The data are consistent with Standard Model background contributions, and at 95% confidence level the search sets observed (expected) upper limits of 1.7 × 10−4 (2.4 × 10−4) on the t → uZ branching ratio and 2.4 × 10−4 (3.2 × 10−4) on the t → cZ branching ratio, constituting the most stringent limits to date.[Figure not available: see fulltext.].
AB - A search for flavour-changing neutral-current processes in top-quark decays is presented. Data collected with the ATLAS detector from proton-proton collisions at the Large Hadron Collider at a centre-of-mass energy of s=13 TeV, corresponding to an integrated luminosity of 36.1 fb−1, are analysed. The search is performed using top-quark pair events, with one top quark decaying through the t → qZ (q = u, c) flavour-changing neutral-current channel, and the other through the dominant Standard Model mode t → bW. Only Z boson decays into charged leptons and leptonic W boson decays are considered as signal. Consequently, the final-state topology is characterized by the presence of three isolated charged leptons (electrons or muons), at least two jets, one of the jets originating from a b-quark, and missing transverse momentum from the undetected neutrino. The data are consistent with Standard Model background contributions, and at 95% confidence level the search sets observed (expected) upper limits of 1.7 × 10−4 (2.4 × 10−4) on the t → uZ branching ratio and 2.4 × 10−4 (3.2 × 10−4) on the t → cZ branching ratio, constituting the most stringent limits to date.[Figure not available: see fulltext.].
U2 - 10.1007/JHEP07(2018)176
DO - 10.1007/JHEP07(2018)176
M3 - Journal article
SN - 1126-6708
VL - 2018
JO - Journal of High Energy Physics (Online)
JF - Journal of High Energy Physics (Online)
IS - 7
M1 - 176
ER -