Search for new phenomena in final states with large jet multiplicities and missing transverse momentum using $\sqrt(s) = 13$ TeV proton$-$proton collisions recorded by ATLAS in Run 2 of the LHC

The ATLAS collaboration
JHEP 10 (2020) 062, 2020.

Abstract
Results of a search for new particles decaying into eight or more jets and moderate missing transverse momentum are presented. The analysis uses 139 fb$^{-1}$ of proton$-$proton collision data at $\sqrt{s} = 13$ TeV collected by the ATLAS experiment at the Large Hadron Collider between 2015 and 2018. The selection rejects events containing isolated electrons or muons, and makes requirements according to the number of $b$-tagged jets and the scalar sum of masses of large-radius jets. The search extends previous analyses both in using a larger dataset and by employing improved jet and missing transverse momentum reconstruction methods which more cleanly separate signal from background processes. No evidence for physics beyond the Standard Model is found. The results are interpreted in the context of supersymmetry-inspired simplified models, significantly extending the limits on the gluino mass in those models. In particular, limits on the gluino mass are set at 2 TeV when the lightest neutralino is nearly massless in a model assuming a two-step cascade decay via the lightest chargino and second-lightest neutralino.

  • Post-fit Signal Region Yields (Multi-bin 8 jet)

    Data from Figure 8a.

    10.17182/hepdata.93733.v1/t1

    Post-fit yields for data and prediction in each of the multi-bin signal regions for the 8 jet regions.

  • Post-fit Signal Region Yields (Multi-bin 9 jet)

    Data from Figure 8b.

    10.17182/hepdata.93733.v1/t2

    Post-fit yields for data and prediction in each of the multi-bin signal regions for the 9 jet regions.

  • Post-fit Signal Region Yields (Multi-bin 10 jet)

    Data from Figure 8c.

    10.17182/hepdata.93733.v1/t3

    Post-fit yields for data and prediction in each of the multi-bin signal regions for the 10 jet regions.

  • Post-fit Signal Region Yields (Single-bin)

    Data from Figure 8d.

    10.17182/hepdata.93733.v1/t4

    Post-fit yields for data and prediction in each of the single-bin signal regions of the analysis.

  • Exclusion Limits (Obs.) Two-step

    Data from Figure 10a.

    10.17182/hepdata.93733.v1/t5

    Observed 95% confidence level limit for the two-step signal grid.

  • Exclusion Limits (Obs. +1 sigma) Two-step

    Data from Figure 10a.

    10.17182/hepdata.93733.v1/t6

    Observed 95% confidence level limit for the two-step signal grid with the signal cross section increased by one sigma.

  • Exclusion Limits (Obs. -1 sigma) Two-step

    Data from Figure 10a.

    10.17182/hepdata.93733.v1/t7

    Observed 95% confidence level limit for the two-step signal grid with the signal cross section decreased by one sigma.

  • Exclusion Limits (Exp.) Two-step

    Data from Figure 10a.

    10.17182/hepdata.93733.v1/t8

    Expected 95% confidence level limit for the two-step signal grid.

  • Exclusion Limits (Exp. +1 sigma) Two-step

    Data from Figure 10a.

    10.17182/hepdata.93733.v1/t9

    Expected 95% confidence level limit for the two-step signal grid plus one sigma from experimental systematics.

  • Exclusion Limits (Exp. -1 sigma) Two-step

    Data from Figure 10a.

    10.17182/hepdata.93733.v1/t10

    Expected 95% confidence level limit for the two-step signal grid minus one sigma from experimental systematics.

  • Exclusion Limits (Obs.) Gtt

    Data from Figure 10b.

    10.17182/hepdata.93733.v1/t11

    Observed 95% confidence level limit for the Gtt signal grid.

  • Exclusion Limits (Obs. +1 sigma) Gtt

    Data from Figure 10b.

    10.17182/hepdata.93733.v1/t12

    Observed 95% confidence level limit for the Gtt signal grid with the signal cross section increased by one sigma.

  • Exclusion Limits (Obs. -1 sigma) Gtt

    Data from Figure 10b.

    10.17182/hepdata.93733.v1/t13

    Observed 95% confidence level limit for the Gtt signal grid with the signal cross section decreased by one sigma.

  • Exclusion Limits (Exp.) Gtt

    Data from Figure 10b.

    10.17182/hepdata.93733.v1/t14

    Expected 95% confidence level limit for the Gtt signal grid.

  • Exclusion Limits (Exp. +1 sigma) Gtt

    Data from Figure 10b.

    10.17182/hepdata.93733.v1/t15

    Expected 95% confidence level limit for the Gtt signal grid plus one sigma from experimental systematics.

  • Exclusion Limits (Exp. -1 sigma) Gtt

    Data from Figure 10b.

    10.17182/hepdata.93733.v1/t16

    Expected 95% confidence level limit for the Gtt signal grid minus one sigma from experimental systematics.

  • Exclusion Limits (Obs.) RPV

    Data from Figure 10c.

    10.17182/hepdata.93733.v1/t17

    Observed 95% confidence level limit for the RPV signal grid.

  • Exclusion Limits (Obs. +1 sigma) RPV

    Data from Figure 10c.

    10.17182/hepdata.93733.v1/t18

    Observed 95% confidence level limit for the RPV signal grid with the signal cross section increased by one sigma.

  • Exclusion Limits (Obs. -1 sigma) RPV

    Data from Figure 10c.

    10.17182/hepdata.93733.v1/t19

    Observed 95% confidence level limit for the RPV signal grid with the signal cross section decreased by one sigma.

  • Exclusion Limits (Exp.) RPV

    Data from Figure 10c.

    10.17182/hepdata.93733.v1/t20

    Expected 95% confidence level limit for the RPV signal grid.

  • Exclusion Limits (Exp. +1 sigma) RPV

    Data from Figure 10c.

    10.17182/hepdata.93733.v1/t21

    Expected 95% confidence level limit for the RPV signal grid plus one sigma from experimental systematics.

  • Exclusion Limits (Exp. -1 sigma) RPV

    Data from Figure 10c.

    10.17182/hepdata.93733.v1/t22

    Expected 95% confidence level limit for the RPV signal grid minus one sigma from experimental systematics.

  • Exclusion Limits (Obs.) Two-step (Single-bin)

    Data from aux material, Figure 1a.

    10.17182/hepdata.93733.v1/t23

    Observed 95% confidence level limit for the two-step signal grid.

  • Exclusion Limits (Exp.) Two-step (Single-bin)

    Data from aux material, Figure 1a.

    10.17182/hepdata.93733.v1/t24

    Expected 95% confidence level limit for the two-step signal grid.

  • Exclusion Limits (Obs.) Gtt (Single-bin)

    Data from aux material, Figure 1b.

    10.17182/hepdata.93733.v1/t25

    Observed 95% confidence level limit for the Gtt signal grid.

  • Exclusion Limits (Exp.) Gtt (Single-bin)

    Data from aux material, Figure 1b.

    10.17182/hepdata.93733.v1/t26

    Expected 95% confidence level limit for the Gtt signal grid.

  • Exclusion Limits (Obs.) RPV (Single-bin)

    Data from aux material, Figure 1c.

    10.17182/hepdata.93733.v1/t27

    Observed 95% confidence level limit for the RPV signal grid.

  • Exclusion Limits (Exp.) RPV (Single-bin)

    Data from aux material, Figure 1c.

    10.17182/hepdata.93733.v1/t28

    Expected 95% confidence level limit for the RPV signal grid.

  • SR Kinematics 1

    Data from Figure 9a.

    10.17182/hepdata.93733.v1/t29

    $\mathcal{S}(E_{\mathrm{T}}^{\mathrm{miss}})$ distribution in the signal region SR-10ij50-0ib-MJ340. Two benchmark signal models are shown along with the background yields. These models,...

  • SR Kinematics 2

    Data from Figure 9b.

    10.17182/hepdata.93733.v1/t30

    $\mathcal{S}(E_{\mathrm{T}}^{\mathrm{miss}})$ distribution in the signal region SR-12ij50-2ib. Two benchmark signal models are shown along with the background yields. These models,...

  • SR Kinematics 3

    Data from Figure 9c.

    10.17182/hepdata.93733.v1/t31

    $\mathcal{S}(E_{\mathrm{T}}^{\mathrm{miss}})$ distribution in the signal region SR-9ij80-0ib. Two benchmark signal models are shown along with the background yields. These models,...

  • Cutflow 1

    Data from aux material, Table 1.

    10.17182/hepdata.93733.v1/t32

    Number of signal events expected for $139 \, \mathrm{fb}^{-1} $ after different analysis selections in the signal region SR-8ij50-0ib-MJ500. This...

  • Cutflow 2

    Data from aux material, Table 2.

    10.17182/hepdata.93733.v1/t33

    Number of signal events expected for $139 \, \mathrm{fb}^{-1} $ after different analysis selections in the signal region SR-9ij50-0ib-MJ340. This...

  • Cutflow 3

    Data from aux material, Table 3.

    10.17182/hepdata.93733.v1/t34

    Number of signal events expected for $139 \, \mathrm{fb}^{-1} $ after different analysis selections in the signal region SR-10ij50-0ib-MJ340. This...

  • Cutflow 4

    Data from aux material, Table 4.

    10.17182/hepdata.93733.v1/t35

    Number of signal events expected for $139 \, \mathrm{fb}^{-1} $ after different analysis selections in the signal region SR-10ij50-0ib-MJ500. This...

  • Cutflow 5

    Data from aux material, Table 5.

    10.17182/hepdata.93733.v1/t36

    Number of signal events expected for $139 \, \mathrm{fb}^{-1} $ after different analysis selections in the signal region SR-10ij50-1ib-MJ500. This...

  • Cutflow 6

    Data from aux material, Table 6.

    10.17182/hepdata.93733.v1/t37

    Number of signal events expected for $139 \, \mathrm{fb}^{-1} $ after different analysis selections in the signal region SR-11ij50-0ib. This...

  • Cutflow 7

    Data from aux material, Table 7.

    10.17182/hepdata.93733.v1/t38

    Number of signal events expected for $139 \, \mathrm{fb}^{-1} $ after different analysis selections in the signal region SR-12ij50-2ib. This...

  • Cutflow 8

    Data from aux material, Table 8.

    10.17182/hepdata.93733.v1/t39

    Number of signal events expected for $139 \, \mathrm{fb}^{-1} $ after different analysis selections in the signal region SR-9ij80-0ib. This...

  • Acceptance 1

    Data from aux material, Figure 6a.

    10.17182/hepdata.93733.v1/t40

    Acceptance for the signal region SR-8ij50-0ib-MJ500 showing the acceptance for the complete two-step signal grid.

  • Efficiency 1

    Data from aux material, Figure 6b.

    10.17182/hepdata.93733.v1/t41

    Efficiency for the signal region SR-8ij50-0ib-MJ500 showing the efficiency for the complete two-step signal grid.

  • Acceptance 2

    Data from aux material, Figure 7a.

    10.17182/hepdata.93733.v1/t42

    Acceptance for the signal region SR-9ij50-0ib-MJ340 showing the acceptance for the complete two-step signal grid.

  • Efficiency 2

    Data from aux material, Figure 7b.

    10.17182/hepdata.93733.v1/t43

    Efficiency for the signal region SR-9ij50-0ib-MJ340 showing the efficiency for the complete two-step signal grid.

  • Acceptance 3

    Data from aux material, Figure 8a.

    10.17182/hepdata.93733.v1/t44

    Acceptance for the signal region SR-10ij50-0ib-MJ340 showing the acceptance for the complete two-step signal grid.

  • Efficiency 3

    Data from aux material, Figure 8b.

    10.17182/hepdata.93733.v1/t45

    Efficiency for the signal region SR-10ij50-0ib-MJ340 showing the efficiency for the complete two-step signal grid.

  • Acceptance 4

    Data from aux material, Figure 9a.

    10.17182/hepdata.93733.v1/t46

    Acceptance for the signal region SR-10ij50-0ib-MJ500 showing the acceptance for the complete two-step signal grid.

  • Efficiency 4

    Data from aux material, Figure 9b.

    10.17182/hepdata.93733.v1/t47

    Efficiency for the signal region SR-10ij50-0ib-MJ500 showing the efficiency for the complete two-step signal grid.

  • Acceptance 5

    Data from aux material, Figure 10a.

    10.17182/hepdata.93733.v1/t48

    Acceptance for the signal region SR-10ij50-1ib-MJ500 showing the acceptance for the complete two-step signal grid.

  • Efficiency 5

    Data from aux material, Figure 10b.

    10.17182/hepdata.93733.v1/t49

    Efficiency for the signal region SR-10ij50-1ib-MJ500 showing the efficiency for the complete two-step signal grid.

  • Acceptance 6

    Data from aux material, Figure 11a.

    10.17182/hepdata.93733.v1/t50

    Acceptance for the signal region SR-11ij50-0ib showing the acceptance for the complete two-step signal grid.

  • Efficiency 6

    Data from aux material, Figure 11b.

    10.17182/hepdata.93733.v1/t51

    Efficiency for the signal region SR-11ij50-0ib showing the efficiency for the complete two-step signal grid.

  • Acceptance 7

    Data from aux material, Figure 12a.

    10.17182/hepdata.93733.v1/t52

    Acceptance for the signal region SR-12ij50-2ib showing the acceptance for the complete two-step signal grid.

  • Efficiency 7

    Data from aux material, Figure 12b.

    10.17182/hepdata.93733.v1/t53

    Efficiency for the signal region SR-12ij50-2ib showing the efficiency for the complete two-step signal grid.

  • Acceptance 8

    Data from aux material, Figure 13a.

    10.17182/hepdata.93733.v1/t54

    Acceptance for the signal region SR-9ij80-0ib showing the acceptance for the complete two-step signal grid.

  • Efficiency 8

    Data from aux material, Figure 13b.

    10.17182/hepdata.93733.v1/t55

    Efficiency for the signal region SR-9ij80-0ib showing the efficiency for the complete two-step signal grid.

  • Normalisation Factors

    Data from Figure 5.

    10.17182/hepdata.93733.v1/t56

    The normalisation factors for the dominant backgrounds of the analysis in each of the multi-bin and single-bin regions.

  • Post-fit Validation Single-bin Region Yields (VRA)

    Data from Figure 7a.

    10.17182/hepdata.93733.v1/t57

    Post-fit yields for data and prediction in each of the single-bin validation regions to test the $N_{\mathrm{jet}}$ extraction.

  • Post-fit Validation Single-bin Region Yields (VRB)

    Data from Figure 7b.

    10.17182/hepdata.93733.v1/t58

    Post-fit yields for data and prediction in each of the single-bin validation regions to test the $\mathcal{S}(E_{\mathrm{T}}^{\mathrm{miss}})$ extrapolation.

  • Post-fit Validation Multi-bin Region Yields (VRA)

    Data from Figure 6a.

    10.17182/hepdata.93733.v1/t59

    Post-fit yields for data and prediction in each of the multi-bin validation regions to test the $N_{\mathrm{jet}}$ extraction.

  • Post-fit Validation Multi-bin Region Yields (VRB)

    Data from Figure 6b.

    10.17182/hepdata.93733.v1/t60

    Post-fit yields for data and prediction in each of the multi-bin validation regions to test the $\mathcal{S}(E_{\mathrm{T}}^{\mathrm{miss}})$ extrapolation.

  • Observed CLs From Best Expected Signal Regions 1.

    Data from aux material, Figure 5a.

    10.17182/hepdata.93733.v1/t61

    The observed Cls from the best expected signal regions for the two-step decay.

  • Observed CLs From Best Expected Signal Regions 2.

    Data from aux material, Figure 5b.

    10.17182/hepdata.93733.v1/t62

    The observed Cls from the best expected signal regions for the Gtt decay.

  • Observed CLs From Best Expected Signal Regions 3.

    Data from aux material, Figure 5c.

    10.17182/hepdata.93733.v1/t63

    The observed Cls from the best expected signal regions for the RPV decay.

  • Single-bin SRs Summary Backgrounds

    Data from Table 9.

    10.17182/hepdata.93733.v1/t64

    Number of events in each signal region broken down by background type and the number of observed data events.

  • Signal Channel Upper Limits

    Data from Table 10.

    10.17182/hepdata.93733.v1/t65

    From left to right; the $95\%$ CL upper limits on the visible cross section (${\langle \epsilon\sigma \rangle}^{95}_{obs}$) and on the...

  • Event Display 13 Jets

    Data from aux material, Figure 2.

    10.17182/hepdata.93733.v1/t66

    Visualisation of the highest jet multiplicity event selected in signal regions targeting long cascade decays of pair-produced gluinos. This event...

  • Event Display 16 Jets

    Data from aux material, Figure 2.

    10.17182/hepdata.93733.v1/t67

    Visualisation of the highest jet multiplicity event selected in a control region used to make predictions of the background from...

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