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Search for $t\bar{t}$ resonances in fully hadronic final states in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector

The collaboration
2020.

Abstract (data abstract)
This paper presents a search for new heavy particles decaying into a pair of top quarks using 139 fb$^{-1}$ of proton--proton collision data recorded at a centre-of-mass energy of $\sqrt{s} = 13$ TeV with the ATLAS detector at the Large Hadron Collider. The search is performed using events consistent with pair production of high-transverse-momentum top quarks and their subsequent decays into the fully hadronic final states. The analysis is optimized for resonances decaying into a $t\bar{t}$ pair with mass above 1.4 TeV, exploiting a dedicated multivariate technique with jet substructure to identify hadronically decaying top quarks using large-radius jets and evaluating the background expectation from data. No significant deviation from the background prediction is observed. Limits are set on the production cross-section times branching fraction for the new $Z'$ boson in a topcolor-assisted-technicolor model. The $Z'$ boson masses below 3.9 and 4.7 TeV are excluded at 95% confidence level for the decay widths of 1% and 3%, respectively.

• #### Figure 2a

Data from Figure 2(a)

10.17182/hepdata.94415.v1/t1

Acceptance and acceptance times selection efficiency as a function of $m^{gen}_{t\bar{t}}$ in SR$1b$. The acceptance is measured as the fraction...

• #### Figure 2b

Data from Figure 2(b)

10.17182/hepdata.94415.v1/t2

Acceptance and acceptance times selection efficiency as a function of $m^{gen}_{t\bar{t}}$ in SR$2b$. The acceptance is measured as the fraction...

• #### Figure 3a

Data from Figure 3(a)

10.17182/hepdata.94415.v1/t3

Observed $m_{t\bar{t}}^{reco}$ distributions in data for SR$1b$, shown together with the result of the fit with the three-shape-parameter function. The...

• #### Figure 3b

Data from Figure 3(b)

10.17182/hepdata.94415.v1/t4

Observed $m_{t\bar{t}}^{reco}$ distributions in data for SR$2b$, shown together with the result of the fit with the three-shape-parameter function. The...

• #### Figure 4

Data from Figure 4

10.17182/hepdata.94415.v1/t5

Observed and expected upper limits on the cross-section times branching fraction of the $Z'_{TC2} \rightarrow t\bar{t}$ as a function of...

• #### Background Fit Parameters

Data from background fit in Figure 3

10.17182/hepdata.94415.v1/t6

Fit parameter values obtained from fits to data in the two signal regions. The fit function is \$f(x) = p_{0}...