Search for $t\bar tH/A \rightarrow t\bar tt\bar t$ production in the multilepton final state in proton-proton collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector

The ATLAS collaboration
JHEP 07 (2023) 203, 2023.

Abstract
A search for a new heavy scalar or pseudo-scalar Higgs boson ($H/A$) produced in association with a pair of top quarks, with the Higgs boson decaying into a pair of top quarks ($H/A\rightarrow t\bar{t}$) is reported. The search targets a final state with exactly two leptons with same-sign electric charges or at least three leptons. The analysed dataset corresponds to an integrated luminosity of 139 fb$^{-1}$ of proton-proton collisions collected at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. Two multivariate classifiers are used to separate the signal from the background. No significant excess of events over the Standard Model expectation is observed. The results are interpreted in the context of a type-II two-Higgs-doublet model. The observed (expected) upper limits at 95% confidence level on the $t\bar{t}H/A$ production cross-section times the branching ratio of $H/A\rightarrow t\bar{t}$ range between 14 (10) fb and 6 (5) fb for a heavy Higgs boson with mass between 400 GeV and 1000 GeV, respectively. Assuming that only one particle, either the scalar $H$ or the pseudo-scalar $A$, contributes to the $t\bar{t}t\bar{t}$ final state, values of $\tan\beta$ below 1.2 or 0.5 are excluded for a mass of 400 GeV or 1000 GeV, respectively. These exclusion ranges increase to $\tan\beta$ below 1.6 or 0.6 when both particles are considered.

  • Figure 2a

    Data from Figure 2a

    10.17182/hepdata.135458.v1/t1

    Pre-fit comparison between data and background in the baseline SR for two of the variables used as input for the...

  • Figure 2b

    Data from Figure 2b

    10.17182/hepdata.135458.v1/t2

    Pre-fit comparison between data and background in the baseline SR for two of the variables used as input for the...

  • Figure 3a

    Data from Figure 3a

    10.17182/hepdata.135458.v1/t3

    Pre-fit comparison between data and background in the baseline SR for two of the variables used as input for the...

  • Figure 3b

    Data from Figure 3b

    10.17182/hepdata.135458.v1/t4

    Pre-fit comparison between data and background in the baseline SR for two of the variables used as input for the...

  • Figure 4a: CR HF e

    Data from Figure 4a

    10.17182/hepdata.135458.v1/t5

    Data and post-fit background comparison for the distributions of the discriminant variables fitted in the control regions obtained with the...

  • Figure 4b: CR HF mu

    Data from Figure 4b

    10.17182/hepdata.135458.v1/t6

    Data and post-fit background comparison for the distributions of the discriminant variables fitted in the control regions obtained with the...

  • Figure 4c: CR Conv

    Data from Figure 4c

    10.17182/hepdata.135458.v1/t7

    Data and post-fit background comparison for the distributions of the discriminant variables fitted in the control regions obtained with the...

  • Figure 4d: CR ttW

    Data from Figure 4d

    10.17182/hepdata.135458.v1/t8

    Data and post-fit background comparison for the distributions of the discriminant variables fitted in the control regions obtained with the...

  • Figure 4e: CR lowBDT

    Data from Figure 4e

    10.17182/hepdata.135458.v1/t9

    Data and post-fit background comparison for the distributions of the discriminant variables fitted in the control regions obtained with the...

  • Figure 5a: ttW VR

    Data from Figure 5a

    10.17182/hepdata.135458.v1/t10

    Data and post-fit background comparison obtained with the background-only fit in the validation region defined for ttW+jets events: number of...

  • Figure 5b: ttW VR

    Data from Figure 5b

    10.17182/hepdata.135458.v1/t11

    Data and post-fit background comparison obtained with the background-only fit in the validation region defined for ttW+jets events: SM BDT.

  • Figure 6a

    Data from Figure 6a

    10.17182/hepdata.135458.v1/t12

    Data and post-fit background comparison obtained with the background-only fit to the BSM SR for the BSM pBDT distribution used...

  • Figure 6b

    Data from Figure 6b

    10.17182/hepdata.135458.v1/t13

    Data and post-fit background comparison obtained with the background-only fit to the BSM SR for the BSM pBDT distribution used...

  • Figure 7

    Data from Figure 7

    10.17182/hepdata.135458.v1/t14

    Observed (black solid line) and expected (black dashed line) 95% CL upper limits on the ttH/A cross-section times branching fraction...

  • Figure 8a

    Data from Figure 8a

    10.17182/hepdata.135458.v1/t15

    Observed (red line) and expected (black dashed line) exclusion regions at 95% CL in the tan(beta) versus mass plane assuming...

  • Figure 8b

    Data from Figure 8b

    10.17182/hepdata.135458.v1/t16

    Observed (red line) and expected (black dashed line) exclusion regions at 95% CL in the tan(beta) versus mass plane assuming...

  • Figure Aux 1a

    Data from Figure Aux 1a

    10.17182/hepdata.135458.v1/t17

    Data and post-fit background comparison obtained with the background-only fit to the BSM SR for the BSM pBDT distribution used...

  • Figure Aux 1b

    Data from Figure Aux 1b

    10.17182/hepdata.135458.v1/t18

    Data and post-fit background comparison obtained with the background-only fit to the BSM SR for the BSM pBDT distribution used...

  • Figure Aux 1c

    Data from Figure Aux 1c

    10.17182/hepdata.135458.v1/t19

    Data and post-fit background comparison obtained with the background-only fit to the BSM SR for the BSM pBDT distribution used...

  • Figure Aux 1d

    Data from Figure Aux 1d

    10.17182/hepdata.135458.v1/t20

    Data and post-fit background comparison obtained with the background-only fit to the BSM SR for the BSM pBDT distribution used...

  • Figure Aux 1e

    Data from Figure Aux 1e

    10.17182/hepdata.135458.v1/t21

    Data and post-fit background comparison obtained with the background-only fit to the BSM SR for the BSM pBDT distribution used...

  • Figure Aux 6

    Data from Figure Aux 6

    10.17182/hepdata.135458.v1/t22

    Observed (red line) and expected (black dashed line) exclusion regions at 95% CL in the tan(beta) versus mass plane assuming...

  • Table Aux 02

    Data from Table Aux 02

    10.17182/hepdata.135458.v1/t23

    The product of acceptance and efficiency (A×ε), defined as the number of signal events satisfying the full set of selection...

Loading Data...

Ask a Question


Your question will be emailed to those involved with the submission. Please mention the relevant table.


Please log in to HEPData to send a question.