PT Journal
AU ATLAS Collaboration (Aad, Gea
   Aparisi Pozo, JA
   Bailey, AJ
   Cabrera Urban, S
   Castillo, FL
   Castillo Gimenez, V
   Costa, MJ
   Escobar, C
   Estrada Pastor, O
   Ferrer, A
   Fiorini, L
   Fullana Torregrosa, E
   Fuster, J
   Garcia, C
   Garcia Navarro, JE
   Gonzalez de la Hoz, S
   Gonzalvo Rodriguez, GR
   Guerrero Rojas, JGR
   Higon-Rodriguez, E
   Lacasta, C
   Lozano Bahilo, JJ
   Madaffari, D
   Mamuzic, J
   Marti-Garcia, S
   Martinez Agullo, P
   Mitsou, VA
   Moreno Llacer, M
   Poveda, J
   Rodriguez Bosca, S
   Ruiz-Martinez, A
   Salt, J
   Santra, A
   Sayago Galvan, I
   Soldevila, U
   Sanchez, J
   Valero, A
   Valls Ferrer, JA
   Vos, M
TI Search for a scalar partner of the top quark in the all-hadronic t(t)over-bar plus missing transverse momentum final state at root s=13 TeV with the ATLAS detector
SO European Physical Journal C
JI Eur. Phys. J. C
PY 2020
BP 737 - 44pp
VL 80
IS 8
DI 10.1140/epjc/s10052-020-8102-8
LA English
AB 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 t (t) over bar plus missing transverse momentum final state is presented. The analysis of 139 fb(-1) of root 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) over tilde -> t(*) (chi) over tilde (0)(1), with t(*) denoting an on-shell (off-shell) top quark and (chi) over tilde (0)(1) the lightest neutralino. Three specific event selections are optimised for the following scenarios. In the scenario where m((t) over tilde) > m(t) + m((chi) over tilde 10), top squark masses are excluded in the range 400-1250 GeV for (chi) over tilde (0)(1) masses below 200 GeV at 95% confidence level. In the situation where m((t) over tilde) similar to m(t) + m((chi) over tilde 10), top squarkmasses in the range 300-630 GeV are excluded, while in the case where m((t) over tilde) < m(W) + m(b) + m(<(chi)over tilde>10) (with m((t) over tilde) – m((chi) over tilde 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.
ER