Search in diphoton and dielectron final states for displaced production of Higgs or $Z$ bosons with the ATLAS detector in $\sqrt{s} = 13$ TeV $pp$ collisions

The ATLAS collaboration
Phys.Rev.D 108 (2023) 012012, 2023.

Abstract
A search is presented for displaced production of Higgs bosons or $Z$ bosons, originating from the decay of a neutral long-lived particle (LLP) and reconstructed in the decay modes $H\rightarrow \gamma\gamma$ and $Z\rightarrow ee$. The analysis uses the full Run 2 data set of proton$-$proton collisions delivered by the LHC at an energy of $\sqrt{s}=13$ TeV between 2015 and 2018 and recorded by the ATLAS detector, corresponding to an integrated luminosity of 139 fb$^{-1}$. Exploiting the capabilities of the ATLAS liquid argon calorimeter to precisely measure the arrival times and trajectories of electromagnetic objects, the analysis searches for the signature of pairs of photons or electrons which arise from a common displaced vertex and which arrive after some delay at the calorimeter. The results are interpreted in a gauge-mediated supersymmetry breaking model with pair-produced higgsinos that decay to LLPs, and each LLP subsequently decays into either a Higgs boson or a $Z$ boson. The final state includes at least two particles that escape direct detection, giving rise to missing transverse momentum. No significant excess is observed above the background expectation. The results are used to set upper limits on the cross section for higgsino pair production, up to a $\tilde\chi^0_1$ mass of 369 (704) GeV for decays with 100% branching ratio of $\tilde\chi^0_1$ to Higgs ($Z$) bosons for a $\tilde\chi^0_1$ lifetime of 2 ns. A model-independent limit is also set on the production of pairs of photons or electrons with a significant delay in arrival at the calorimeter.

  • Table 1

    Data from Figure 8a

    10.17182/hepdata.135829.v1/t1

    Average timing distributions for SR data and the estimated background as determined by the background-only fit, in each of the...

  • Table 2

    Data from Figure 8b

    10.17182/hepdata.135829.v1/t2

    Average timing distributions for SR data and the estimated background as determined by the background-only fit, in each of the...

  • Table 3

    Data from Figure 8c

    10.17182/hepdata.135829.v1/t3

    Average timing distributions for SR data and the estimated background as determined by the background-only fit, in each of the...

  • Table 4

    Data from Figure 8d

    10.17182/hepdata.135829.v1/t4

    Average timing distributions for SR data and the estimated background as determined by the background-only fit, in each of the...

  • Table 5

    Data from Figure 8e

    10.17182/hepdata.135829.v1/t5

    Average timing distributions for SR data and the estimated background as determined by the background-only fit, in each of the...

  • Table 6

    Data from Figure 9a

    10.17182/hepdata.135829.v1/t6

    The 95% CL limits on $\sigma(pp \rightarrow \tilde\chi^0_1 \tilde\chi^0_1$) in fb as a function of $\tilde\chi^0_1$ mass (left) and $\tilde\chi^0_1$...

  • Table 7

    Data from Figure 9a

    10.17182/hepdata.135829.v1/t7

    The 95% CL limits on $\sigma(pp \rightarrow \tilde\chi^0_1 \tilde\chi^0_1$) in fb as a function of $\tilde\chi^0_1$ mass (left) and $\tilde\chi^0_1$...

  • Table 8

    Data from Figure 9a

    10.17182/hepdata.135829.v1/t8

    The 95% CL limits on $\sigma(pp \rightarrow \tilde\chi^0_1 \tilde\chi^0_1$) in fb as a function of $\tilde\chi^0_1$ mass (left) and $\tilde\chi^0_1$...

  • Table 9

    Data from Figure 9a

    10.17182/hepdata.135829.v1/t9

    The 95% CL limits on $\sigma(pp \rightarrow \tilde\chi^0_1 \tilde\chi^0_1$) in fb as a function of $\tilde\chi^0_1$ mass (left) and $\tilde\chi^0_1$...

  • Table 10

    Data from Figure 9b

    10.17182/hepdata.135829.v1/t10

    The 95% CL limits on $\sigma(pp \rightarrow \tilde\chi^0_1 \tilde\chi^0_1$) in fb as a function of $\tilde\chi^0_1$ mass (left) and $\tilde\chi^0_1$...

  • Table 11

    Data from Figure 9b

    10.17182/hepdata.135829.v1/t11

    The 95% CL limits on $\sigma(pp \rightarrow \tilde\chi^0_1 \tilde\chi^0_1$) in fb as a function of $\tilde\chi^0_1$ mass (left) and $\tilde\chi^0_1$...

  • Table 12

    Data from Figure 9b

    10.17182/hepdata.135829.v1/t12

    The 95% CL limits on $\sigma(pp \rightarrow \tilde\chi^0_1 \tilde\chi^0_1$) in fb as a function of $\tilde\chi^0_1$ mass (left) and $\tilde\chi^0_1$...

  • Table 13

    Data from Figure 9b

    10.17182/hepdata.135829.v1/t13

    The 95% CL limits on $\sigma(pp \rightarrow \tilde\chi^0_1 \tilde\chi^0_1$) in fb as a function of $\tilde\chi^0_1$ mass (left) and $\tilde\chi^0_1$...

  • Table 14

    Data from Figure 9c

    10.17182/hepdata.135829.v1/t14

    The 95% CL limits on $\sigma(pp \rightarrow \tilde\chi^0_1 \tilde\chi^0_1$) in fb as a function of $\tilde\chi^0_1$ mass (left) and $\tilde\chi^0_1$...

  • Table 15

    Data from Figure 9c

    10.17182/hepdata.135829.v1/t15

    The 95% CL limits on $\sigma(pp \rightarrow \tilde\chi^0_1 \tilde\chi^0_1$) in fb as a function of $\tilde\chi^0_1$ mass (left) and $\tilde\chi^0_1$...

  • Table 16

    Data from Figure 9c

    10.17182/hepdata.135829.v1/t16

    The 95% CL limits on $\sigma(pp \rightarrow \tilde\chi^0_1 \tilde\chi^0_1$) in fb as a function of $\tilde\chi^0_1$ mass (left) and $\tilde\chi^0_1$...

  • Table 17

    Data from Figure 9c

    10.17182/hepdata.135829.v1/t17

    The 95% CL limits on $\sigma(pp \rightarrow \tilde\chi^0_1 \tilde\chi^0_1$) in fb as a function of $\tilde\chi^0_1$ mass (left) and $\tilde\chi^0_1$...

  • Table 18

    Data from Figure 9d

    10.17182/hepdata.135829.v1/t18

    The 95% CL limits on $\sigma(pp \rightarrow \tilde\chi^0_1 \tilde\chi^0_1$) in fb as a function of $\tilde\chi^0_1$ mass (left) and $\tilde\chi^0_1$...

  • Table 19

    Data from Figure 9d

    10.17182/hepdata.135829.v1/t19

    The 95% CL limits on $\sigma(pp \rightarrow \tilde\chi^0_1 \tilde\chi^0_1$) in fb as a function of $\tilde\chi^0_1$ mass (left) and $\tilde\chi^0_1$...

  • Table 20

    Data from Figure 9d

    10.17182/hepdata.135829.v1/t20

    The 95% CL limits on $\sigma(pp \rightarrow \tilde\chi^0_1 \tilde\chi^0_1$) in fb as a function of $\tilde\chi^0_1$ mass (left) and $\tilde\chi^0_1$...

  • Table 21

    Data from Figure 9d

    10.17182/hepdata.135829.v1/t21

    The 95% CL limits on $\sigma(pp \rightarrow \tilde\chi^0_1 \tilde\chi^0_1$) in fb as a function of $\tilde\chi^0_1$ mass (left) and $\tilde\chi^0_1$...

  • Table 22

    Data from Figure 11

    10.17182/hepdata.135829.v1/t22

    The 95% CL limits on $\sigma(pp \rightarrow \tilde\chi^0_1 \tilde\chi^0_1$) in fb as a function of $\tilde\chi^0_1$ branching ratio to the...

  • Table 23

    Data from Figure 11

    10.17182/hepdata.135829.v1/t23

    The 95% CL limits on $\sigma(pp \rightarrow \tilde\chi^0_1 \tilde\chi^0_1$) in fb as a function of $\tilde\chi^0_1$ branching ratio to the...

  • Table 24

    Data from Figure 11

    10.17182/hepdata.135829.v1/t24

    The 95% CL limits on $\sigma(pp \rightarrow \tilde\chi^0_1 \tilde\chi^0_1$) in fb as a function of $\tilde\chi^0_1$ branching ratio to the...

  • Table 25

    Data from Figure 11

    10.17182/hepdata.135829.v1/t25

    The 95% CL limits on $\sigma(pp \rightarrow \tilde\chi^0_1 \tilde\chi^0_1$) in fb as a function of $\tilde\chi^0_1$ branching ratio to the...

  • Table 26

    Data from Figure 10

    10.17182/hepdata.135829.v1/t26

    The 95% CL exclusion limits on the target signal hypothesis, for $\tilde\chi^0_1$ lifetime in ns as a function of $\tilde\chi^0_1$...

  • Table 27

    Data from Figure 10

    10.17182/hepdata.135829.v1/t27

    The 95% CL exclusion limits on the target signal hypothesis, for $\tilde\chi^0_1$ lifetime in ns as a function of $\tilde\chi^0_1$...

  • Table 28

    Data from Figure 10

    10.17182/hepdata.135829.v1/t28

    The 95% CL exclusion limits on the target signal hypothesis, for $\tilde\chi^0_1$ lifetime in ns as a function of $\tilde\chi^0_1$...

  • Table 29

    Data from Figure 10

    10.17182/hepdata.135829.v1/t29

    The 95% CL exclusion limits on the target signal hypothesis, for $\tilde\chi^0_1$ lifetime in ns as a function of $\tilde\chi^0_1$...

  • Table 38

    Data from Figure 10

    10.17182/hepdata.135829.v1/t30

    The 95% CL exclusion limits on the target signal hypothesis, for $\tilde\chi^0_1$ lifetime in ns as a function of $\tilde\chi^0_1$...

  • Table 46

    Data from Figure 10

    10.17182/hepdata.135829.v1/t31

    The 95% CL exclusion limits on the target signal hypothesis, for $\tilde\chi^0_1$ lifetime in ns as a function of $\tilde\chi^0_1$...

  • Table 54

    Data from Figure 10

    10.17182/hepdata.135829.v1/t32

    The 95% CL exclusion limits on the target signal hypothesis, for $\tilde\chi^0_1$ lifetime in ns as a function of $\tilde\chi^0_1$...

  • Table 62

    Data from Figure 10

    10.17182/hepdata.135829.v1/t33

    The 95% CL exclusion limits on the target signal hypothesis, for $\tilde\chi^0_1$ lifetime in ns as a function of $\tilde\chi^0_1$...

  • Table 66

    Data from Figure 10

    10.17182/hepdata.135829.v1/t34

    The 95% CL exclusion limits on the target signal hypothesis, for $\tilde\chi^0_1$ lifetime in ns as a function of $\tilde\chi^0_1$...

  • Table 67

    Data from Figure 10

    10.17182/hepdata.135829.v1/t35

    The 95% CL exclusion limits on the target signal hypothesis, for $\tilde\chi^0_1$ lifetime in ns as a function of $\tilde\chi^0_1$...

  • Table 68

    Data from Figure 10

    10.17182/hepdata.135829.v1/t36

    The 95% CL exclusion limits on the target signal hypothesis, for $\tilde\chi^0_1$ lifetime in ns as a function of $\tilde\chi^0_1$...

  • Table 69

    Data from Figure 10

    10.17182/hepdata.135829.v1/t37

    The 95% CL exclusion limits on the target signal hypothesis, for $\tilde\chi^0_1$ lifetime in ns as a function of $\tilde\chi^0_1$...

  • Table 70

    Auxiliary

    10.17182/hepdata.135829.v1/t38

    Cutflow for an example higgsino signal with mass 225 GeV and lifetime 10 ns, in the H decay mode. Acceptance...

  • Table 71

    Auxiliary

    10.17182/hepdata.135829.v1/t39

    Cutflow for an example higgsino signal with mass 225 GeV and lifetime 10 ns, in the Z decay mode. Acceptance...

  • Table 72

    Auxiliary

    10.17182/hepdata.135829.v1/t40

    Cutflow for an example higgsino signal with mass 225 GeV and lifetime 2 ns, in the H decay mode. Acceptance...

  • Table 73

    Auxiliary

    10.17182/hepdata.135829.v1/t41

    Cutflow for an example higgsino signal with mass 225 GeV and lifetime 2 ns, in the Z decay mode. Acceptance...

  • Table 74

    Auxiliary

    10.17182/hepdata.135829.v1/t42

    Acceptance across the H decay mode signal grid, calculated using truth information. The selection applied corresponds to the model-independent signal...

  • Table 75

    Auxiliary

    10.17182/hepdata.135829.v1/t43

    Acceptance across the Z decay mode signal grid, calculated using truth information. The selection applied corresponds to the model-independent signal...

  • Table 76

    Auxiliary

    10.17182/hepdata.135829.v1/t44

    Efficiency across the H decay mode signal grid, calculated using reco information. The selection applied corresponds to the model-independent signal...

  • Table 77

    Auxiliary

    10.17182/hepdata.135829.v1/t45

    Efficiency across the Z decay mode signal grid, calculated using reco information. The selection applied corresponds to the model-independent signal...

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