PT Journal
AU ATLAS Collaboration (Aad, Gea
   Amos, KR
   Aparisi Pozo, JA
   Bailey, AJ
   Bouchhar, N
   Cabrera Urban, S
   Cantero, J
   Cardillo, F
   Castillo Gimenez, V
   Chitishvili, M
   Costa, MJ
   Didenko
   Escobar, C
   Fiorini, L
   Fullana Torregrosa, E
   Fuster, J
   Garcia, C
   Garcia Navarro, JE
   Gomez Delegido, AJ
   Gonzalez de la Hoz, S
   Gonzalvo Rodriguez, GR
   Guerrero Rojas, JGR
   Lacasta, C
   Marti-Garcia, S
   Martinez Agullo, P
   Miralles Lopez, M
   Mitsou, VA
   Monsonis Romero, L
   Moreno Llacer, M
   Munoz Perez, D
   Navarro-Gonzalez, J
   Poveda, J
   Prades Ibañez, A
   Rubio Jimenez, A
   Ruiz-Martinez, A
   Sabatini, P
   Salt, J
   Sanchez Sebastian, V
   Sayago Galvan, I
   Senthilkumar, V
   Soldevila, U
   Sanchez, J
   Torro Pastor, E
   Valero, A
   Valiente Moreno, E
   Valls Ferrer, JA
   Varriale, L
   Villaplana Perez, M
   Vos, M
TI Observation of four-top-quark production in the multilepton final state with the ATLAS detector
SO European Physical Journal C
JI Eur. Phys. J. C
PY 2023
BP 496 - 35pp
VL 83
IS 6
DI 10.1140/epjc/s10052-023-11573-0
LA English
AB This paper presents the observation of four-topquark (t (t) over bart (t) over bar) production in proton-proton collisions at the LHC. The analysis is performed using an integrated luminosity of 140 fb-1 at a centre-of-mass energy of 13 TeVcollected using the ATLAS detector. Events containing two leptons with the same electric charge or at least three leptons (electrons or muons) are selected. Event kinematics are used to separate signal from background through a multivariate discriminant, and dedicated control regions are used to constrain the dominant backgrounds. The observed (expected) significance of themeasured t (t) over bart (t) over bar signal with respect to the standard model (SM) background-only hypothesis is 6.1 (4.3) standard deviations. The t (t) over bart (t) over bar production cross section is measured to be 22.5(-5.5)(+6.6), consistent with the SM prediction of 12.0 +/- 2.4 fb within 1.8 standard deviations. Data are also used to set limits on the three-top-quark production cross section, being an irreducible background not measured previously, and to constrain the top-Higgs Yukawa coupling and effective field theory operator coefficients that affect t (t) over bart (t) over bar production.
ER