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Search for pair production of scalar leptoquarks decaying into first- or second-generation leptons and top quarks in proton-proton collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector

The collaboration
CERN-EP-2020-160, 2020.

Abstract (data abstract)
Limits on pair production of scalar leptoquarks, each decaying into either an electron or a muon and a top quark. The search is based on 139.0 $\pm$ 2.4 fb$^{-1}$ of pp collisions at $\sqrt{s}$ = 13 TeV recorded in 2015-2018 with the ATLAS detector at the CERN Large Hadron Collider. Data are analysed in the fully hadronic top quark final state, with a focus on the high LQ mass regime for which the top quarks tend to be boosted. The search results are interpreted to provide a limit on the leptoquark mass. Mass limits on leptoquark pair production are also set as a function of the leptoquark decay branching ratio into a charged lepton and a top quark, as opposed to a neutrino and a bottom quark. Basic event selection: - == 2 opposite-sign same-flavour leptons: pT > 100 GeV, in fiducial volume, isolated from jets - >= 2 large-radius jets - dilepton invariant mass > 120 GeV A parameterized boosted decision tree classifier is used to optimize the sensitivity to LQ signal, using event kinematics and jet substructure variables (see paper).

• #### Table 1: LQLQ->tete Cross Section Limit

Data from Figure 5a

10.17182/hepdata.96389.v1/t1

Expected and observed upper limits at the 95% CL on the leptoquark pair production cross section as a function of...

• #### Table 2: LQLQ->tmutmu Cross Section Limit

Data from Figure 5b

10.17182/hepdata.96389.v1/t2

Expected and observed upper limits at the 95% CL on the leptoquark pair production cross section as a function of...

• #### Table 3: Limit on LQ mass vs. B(LQ->te)

Data from Figure 6a

10.17182/hepdata.96389.v1/t3

Expected and observed 95% CL lower limits on the leptoquark mass as a function of the branching ratio $\mathcal{B}$(LQ->$te$).

• #### Table 4: Limit on LQ mass vs. B(LQ->tmu)

Data from Figure 6b

10.17182/hepdata.96389.v1/t4

Expected and observed 95% CL lower limits on the leptoquark mass as a function of the branching ratio $\mathcal{B}$(LQ->$t\mu$).