Search for leptoquark pair production decaying into $te^- \bar{t}e^+$ or $t\mu^- \bar{t}\mu^+$ in multi-lepton final states in $pp$ collisions at 13 TeV with the ATLAS detector

The ATLAS collaboration
Eur.Phys.J.C 84 (2024) 818, 2024.

Abstract (data abstract)
A search for leptoquark pair production decaying into $te^-\bar{t}e^+$ or $t\mu^-\bar{t}\mu^+$ in final states with multiple leptons is presented. The search is based on a dataset of $pp$ collisions at $\sqrt{s}$=13 TeV recorded with the ATLAS detector during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb$^{-1}$. Events are selected with two or more light leptons (electron or muon) and at least two jets out of which at least one jet is identified as coming from a $b$-hadron. Four signal regions, with the requirement of at least three light leptons, are considered based on the number of leptons of a given flavour. The main background processes are estimated using dedicated control regions in a simultaneous fit with the signal regions to data. No excess above the Standard Model background prediction is observed and 95% confidence level limits on the production cross section times branching ratio are derived as a function of the leptoquark mass. Under the assumption of exclusive decays into $te^-$($t\mu^-$), the corresponding lower limit on the scalar mixed-generation leptoquark mass $m_{LQ_{\mathrm{mix}}^{\mathrm{d}}}$ is at 1.58 (1.59) TeV and on the vector leptoquark mass $m_{\tilde{U}_1}$ at 1.67 (1.67) TeV in the minimal coupling scenario and at 1.95 (1.95) TeV in the Yang-Mills scenario.

  • Scalar LQ signal acceptance times efficiency

    Table 11 of the auxiliary material.

    10.17182/hepdata.150507.v1/t1

    Selection efficiency times acceptance summed over two signal regions for the scalar leptoquark signals as a function of $m_{\mathrm{LQ}_{mix}^{\mathrm{d}}}$, assuming...

  • Vector LQ signal acceptance times efficiency

    Table 12 of the auxiliary material.

    10.17182/hepdata.150507.v1/t2

    Selection efficiency times acceptance summed over two signal regions for the vector leptoquark signals as a function of $m_{\tilde{U}_{1}}$, assuming...

  • Cross section upper limit at 95% CL for $tete$

    Figure 9a.

    10.17182/hepdata.150507.v1/t3

    Summary of the observed and expected 95% CL upper limits on the cross section for $\mathrm{LQ}_{\mathrm{mix}}^{\mathrm{d}}$ pair production as a...

  • Cross section upper limit at 95% CL for $t\mu t\mu$

    Figure 9b.

    10.17182/hepdata.150507.v1/t4

    Summary of the observed and expected 95% CL upper limits on the cross section for $\mathrm{LQ}_{\mathrm{mix}}^{\mathrm{d}}$ pair production as a...

  • Summary of observed and expected event yields (postfit) in SRs

    Table 06.

    10.17182/hepdata.150507.v1/t5

    Summary of observed and predicted yields in the four signal region categories. The background prediction is shown after the combined...

  • Summary of observed and expected event yields (prefit) in SRs

    Table 04 of the auxiliary material.

    10.17182/hepdata.150507.v1/t6

    Summary of the data, background and signal yields in the four signal region categories. The background prediction is shown before...

  • Summary of observed and expected event yields (prefit) in CRs

    Table 02 of the auxiliary material.

    10.17182/hepdata.150507.v1/t7

    Summary of the data and background yields in the seven control region categories. The background prediction is shown before the...

  • Summary of observed and expected event yields (postfit) in CRs

    Table 05 of the auxiliary material.

    10.17182/hepdata.150507.v1/t8

    Summary of the data and background yields in the seven control region categories. The background prediction is shown after the...

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