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Search for pair production of heavy vector-like quarks decaying to high-$p_{mathrm{T}}$ $W$ bosons and $b$ quarks in the lepton-plus-jets final state in $pp$ collisions at $\sqrt{s}$=13 TeV with the ATLAS detector

The collaboration
No Journal Information, 2017

Abstract (data abstract)
CERN-LHC, ATLAS. Limits on pair production of a heavy vector-like T quark together with its antiparticle, where the T quark decays to a W boson and a b quark. The search is based on 36.1 +\- 1.2 fb^{-1} of pp collisions at sqrt{s} = 13 TeV recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. Data are analysed in the lepton plus jets final state, including at least one b-tagged jet and a large-radius jet identified as originating from the hadronic decay of a high-momentum W boson. The search is also sensitive to a heavy vector-like B quark, in particular in the decay to Wt and the results are thus reinterpreted to provide limits on the B mass. Mass limits on both T and B production are also set as a function of the decay branching ratios. Basic event selection: - ==1 electron or muon: pT > 30 GeV, in fiducial volume, isolated from jets - Missing transverse momentum > 60 GeV - >=3 small-R jets, with at least one b-tagged - >=1 hadronic W candidate: W-tagged large-R jet not overlapping a b-tagged jet Leptonically and hadronically decaying VLQ candidates are reconstructed (see paper). Additional selection: Signal region (SR): - S_T > 1800 GeV - Delta R(lepton,nu) < 0.7 - | m(Tlep) - m(Thad) | < 300 GeV Control Region (CR): - 1000 GeV < S_T < 1800 GeV - Delta R(lepton,nu) < 0.7 - | m(Tlep) - m(Thad) | < 300 GeV Validation Region (VR): - S_T > 1200 GeV - 0.7 < Delta R(lepton,nu) < 1.5

• Table 0: Final Variable Distribution

Data from Figure 3a

10.17182/hepdata.77271.v1/t1

The leptonic VLQ candidate mass distributions in the signal region after the maximum likelihood fit in the signal region and...

• Table 1: TT->WbWb Cross Section Limit

Data from Figure 4a

10.17182/hepdata.77271.v1/t2

Expected and observed upper limits at the 95% CL on the TT cross section as a function of T quark...

• Table 2: TT Singlet Cross Section Limit

Data from Figure 4b

10.17182/hepdata.77271.v1/t3

Expected and observed upper limits at the 95% CL on the TT cross section as a function of T quark...

• Table 3: BB->WtWt Cross Section Limit

Data from Figure 13a

10.17182/hepdata.77271.v1/t4

Expected and observed upper limits at the 95% CL on the BB cross section as a function of B quark...

• Table 4: BB Singlet Cross Section Limit

Data from Figure 13b

10.17182/hepdata.77271.v1/t5

Expected and observed upper limits at the 95% CL on the BB cross section as a function of B quark...

• Table 5: Limit on T mass vs. BR

Data from Figure 5

10.17182/hepdata.77271.v1/t6

Expected and observed 95% CL lower limits on the mass of the T quark in the branching ratio plane of...

• Table 6: Limit on B mass vs. BR

Data from Figure 6

10.17182/hepdata.77271.v1/t7

Expected and observed 95% CL lower limits on the mass of the B quark in the branching ratio plane of...