Search for heavy particles decaying into a top-quark pair in the fully hadronic final state in $pp$ collisions at $\sqrt{s} =$ 13 TeV with the ATLAS detector

The ATLAS collaboration
Phys.Rev.D 99 (2019) 092004, 2019.

Abstract (data abstract)
A search for new particles decaying into a pair of top quarks is performed using proton-proton collision data recorded with the ATLAS detector at the Large Hadron Collider at a center-of-mass energy of $\sqrt{s}$ = 13 TeV corresponding to an integrated luminosity of 36.1 fb$^{-1}$. Events consistent with top-quark pair production and the fully hadronic decay mode of the top quarks are selected by requiring multiple high transverse momentum jets including those containing b-hadrons. Two analysis techniques, exploiting dedicated top-quark pair reconstruction in different kinematic regimes, are used to optimize the search sensitivity to new hypothetical particles over a wide mass range. The invariant mass distribution of the two reconstructed top-quark candidates is examined for resonant production of new particles with various spins and decay widths. No significant deviation from the Standard Model prediction is observed and limits are set on the production cross-section times branching fraction for new hypothetical $Z^{\prime}$ bosons, dark-matter mediators, Kaluza-Klein gravitons and Kaluza-Klein gluons. By comparing with the predicted production cross-sections, the $Z^{\prime}$ boson in the topcolor-assisted-technicolor model is excluded for masses up to 3.1−3.6 TeV, the dark-matter mediators in a simplified framework are excluded in the mass ranges from 0.8 TeV to 0.9 TeV and from 2.0 TeV to 2.2 TeV, and the Kaluza-Klein gluon is excluded for masses up to 3.4 TeV, depending on the decay widths of the particles.

  • Table 1

    Data from Figure 5 a).

    10.17182/hepdata.89050.v1/t1

    Acceptance times selection efficiency for topcolor-assisted-technicolor Z$^{\prime}_{TC2}$ as a function of top-quark pair mass for all regions A–D in the...

  • Table 2

    Data from Figure 5 b).

    10.17182/hepdata.89050.v1/t2

    Acceptance times selection efficiency for Kaluza-Klein graviton as a function of top-quark pair mass for all regions A–D in the...

  • Table 3

    Data from Figure 5 c).

    10.17182/hepdata.89050.v1/t3

    Acceptance times selection efficiency for Kaluza-Klein gluon Γ=30% as a function of top-quark pair mass for all regions A–D in...

  • Table 4

    Data from Figure 6 a).

    10.17182/hepdata.89050.v1/t4

    Observed top-quark mass distribution and expected background in Region A after the fit (Post-Fit) under the background-only hypothesis for the...

  • Table 5

    Data from Figure 6 b).

    10.17182/hepdata.89050.v1/t5

    Observed top-quark mass distribution and expected background in Region B after the fit (Post-Fit) under the background-only hypothesis for the...

  • Table 6

    Data from Figure 6 c).

    10.17182/hepdata.89050.v1/t6

    Observed top-quark mass distribution and expected background in Region C after the fit (Post-Fit) under the background-only hypothesis for the...

  • Table 7

    Data from Figure 6 d).

    10.17182/hepdata.89050.v1/t7

    Observed top-quark mass distribution and expected background in Region D after the fit (Post-Fit) under the background-only hypothesis for the...

  • Table 8

    Data from Figure 7 a).

    10.17182/hepdata.89050.v1/t8

    Observed top-quark mass distribution and expected background in Region SR1 Medium 1b after the fit (Post-Fit) under the background-only hypothesis...

  • Table 9

    Data from Figure 7 b).

    10.17182/hepdata.89050.v1/t9

    Observed top-quark mass distribution and expected background in Region SR1 Medium 2b after the fit (Post-Fit) under the background-only hypothesis...

  • Table 10

    Data from Figure 7 c).

    10.17182/hepdata.89050.v1/t10

    Observed top-quark mass distribution and expected background in Region SR1 Tight 1b after the fit (Post-Fit) under the background-only hypothesis...

  • Table 11

    Data from Figure 7 d).

    10.17182/hepdata.89050.v1/t11

    Observed top-quark mass distribution and expected background in Region SR1 Tight 2b after the fit (Post-Fit) under the background-only hypothesis...

  • Table 12

    Data from Figure 8 a).

    10.17182/hepdata.89050.v1/t12

    Observed top-quark mass distribution and expected background in Region SR2 Medium 1b after the fit (Post-Fit) under the background-only hypothesis...

  • Table 13

    Data from Figure 8 b).

    10.17182/hepdata.89050.v1/t13

    Observed top-quark mass distribution and expected background in Region SR2 Medium 2b after the fit (Post-Fit) under the background-only hypothesis...

  • Table 14

    Data from Figure 8 c).

    10.17182/hepdata.89050.v1/t14

    Observed top-quark mass distribution and expected background in Region SR2 Tight 1b after the fit (Post-Fit) under the background-only hypothesis...

  • Table 15

    Data from Figure 8 d).

    10.17182/hepdata.89050.v1/t15

    Observed top-quark mass distribution and expected background in Region SR2 Tight 2b after the fit (Post-Fit) under the background-only hypothesis...

  • Table 16

    Data from Figure 9.

    10.17182/hepdata.89050.v1/t16

    Expected and observed upper limits on the cross-section times branching fraction of topcolor-assisted-technicolor Z$^{\prime}_{TC2}$ decaying into top-quark pair as a...

  • Table 17

    Data from Figure 10 a).

    10.17182/hepdata.89050.v1/t17

    Expected and observed upper limits on the cross-section times branching fraction of A1 axial-vector mediator decaying into top-quark pair as...

  • Table 18

    Data from Figure 10 b).

    10.17182/hepdata.89050.v1/t18

    Expected and observed upper limits on the cross-section times branching fraction of V1 vector mediator decaying into top-quark pair as...

  • Table 19

    Data from Figure 11.

    10.17182/hepdata.89050.v1/t19

    Expected and observed upper limits on the cross-section times branching fraction of Kaluza-Klein graviton decaying into top-quark pair as a...

  • Table 20

    Data from Figure 12.

    10.17182/hepdata.89050.v1/t20

    Expected and observed upper limits on the cross-section times branching fraction of Kaluza-Klein gluon decaying into top-quark pair as a...

  • Table 21

    Data from Figure 13 a).

    10.17182/hepdata.89050.v1/t21

    Expected and observed upper limits on cross-section times branching fraction of Kaluza-Klein gluon decaying into top-quark pair as a function...

  • Table 22

    Data from Figure 13 b).

    10.17182/hepdata.89050.v1/t22

    Expected and observed upper limits on cross-section times branching fraction of Kaluza-Klein gluon decaying into top-quark pair as a function...

  • Table 23

    Data from Figure 13 c).

    10.17182/hepdata.89050.v1/t23

    Expected and observed upper limits on cross-section times branching fraction of Kaluza-Klein gluon decaying into top-quark pair as a function...

  • Table 24

    Data from Figure 13 d).

    10.17182/hepdata.89050.v1/t24

    Expected upper limits on cross-section times branching fraction of Kaluza-Klein gluon decaying into top-quark pair as a function of the...

  • Table 25

    Data from Figure 13 e).

    10.17182/hepdata.89050.v1/t25

    Expected upper limits on cross-section times branching fraction of Kaluza-Klein gluon decaying into top-quark pair as a function of the...

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