Search for long-lived charginos based on a disappearing-track signature in $pp$ collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector

The ATLAS collaboration
No Journal Information, 2017

Abstract (data abstract)
CERN-LHC. This paper presents a search for direct electroweak gaugino or gluino pair production with a chargino nearly mass-degenerate with a stable neutralino. It is based on an integrated luminosity of 36.1 fb$^{-1}$ of $pp$ collisions at $\sqrt{s}$ = 13 TeV collected by the ATLAS experiment at the LHC. The final state of interest is a disappearing track accompanied by at least one jet with high transverse momentum from initial-state radiation or by four jets from the gluino decay chain. The use of short track segments reconstructed from the innermost tracking layers significantly improves the sensitivity to short chargino lifetimes. The results are found to be consistent with Standard Model predictions. Exclusion limits are set at 95% confidence level on the mass of charginos and gluinos for different chargino lifetimes. For a pure wino with a lifetime of about 0.2 ns, chargino masses up to 460 GeV are excluded. For the strong production channel, gluino masses up to 1.65 TeV are excluded assuming a chargino mass of 460 GeV and lifetime of 0.2 ns. For the strong production channel, gluino masses up to 1.65 TeV are excluded assuming a chargino mass of 460 GeV and lifetime of 0.2 ns.

  • Tracklet pT EW VR (fake)

    Data from the publication's Figure 7a

    10.17182/hepdata.78375.v2/t1

    Pixel-tracklet $p_{T}$ spectrum of fake tracklet in electroweak channel in the low-Emiss region.

  • Tracklet pT EW VR (muon)

    Data from the publication's Figure 7a

    10.17182/hepdata.78375.v2/t2

    Pixel-tracklet $p_{T}$ spectrum of muon background in electroweak channel in the low-Emiss region.

  • Tracklet pT EW VR (hadron/electron)

    Data from the publication's Figure 7a

    10.17182/hepdata.78375.v2/t3

    Pixel-tracklet $p_{T}$ spectrum of hadron and electron background in electroweak channel in the low-Emiss region.

  • Tracklet pT EW VR (signal)

    Data from the publication's Figure 7a

    10.17182/hepdata.78375.v2/t4

    Pixel-tracklet $p_{T}$ spectrum of signal ($\tau_{\tilde{\chi}_{1}^{\pm}}$ = 0.2 ns and $m_{\tilde{\chi}_{1}^{\pm}}$ = 400 GeV) in electroweak channel in the low-Emiss...

  • Tracklet pT EW VR (total background)

    Data from the publication's Figure 7a

    10.17182/hepdata.78375.v2/t5

    Pixel-tracklet $p_{T}$ spectrum of total background in electroweak channel in the low-Emiss region.

  • Tracklet pT EW VR (obs)

    Data from the publication's Figure 7a

    10.17182/hepdata.78375.v2/t6

    Pixel-tracklet $p_{T}$ spectrum of observed data in electroweak channel in the low-Emiss region.

  • Tracklet pT Strong VR (fake)

    Data from the publication's Figure 7b

    10.17182/hepdata.78375.v2/t7

    Pixel-tracklet $p_{T}$ spectrum of fake tracklet in strong channel in the low-Emiss region.

  • Tracklet pT Strong VR (muon)

    Data from the publication's Figure 7b

    10.17182/hepdata.78375.v2/t8

    Pixel-tracklet $p_{T}$ spectrum of muon background in strong channel in the low-Emiss region.

  • Tracklet pT Strong VR (hadron/electron)

    Data from the publication's Figure 7b

    10.17182/hepdata.78375.v2/t9

    Pixel-tracklet $p_{T}$ spectrum of hadron and electron background in strong channel in the low-Emiss region.

  • Tracklet pT Strong VR (signal)

    Data from the publication's Figure 7b

    10.17182/hepdata.78375.v2/t10

    Pixel-tracklet $p_{T}$ spectrum of signal ($m_{\tilde{g}}$ = 1600 GeV, $m_{\tilde{\chi}_{1}^{\pm}} = 500 GeV$) in strong channel in the low-Emiss region.

  • Tracklet pT Strong VR (total background)

    Data from the publication's Figure 7b

    10.17182/hepdata.78375.v2/t11

    Pixel-tracklet $p_{T}$ spectrum of total background in strong channel in the low-Emiss region.

  • Tracklet pT Strong VR (obs)

    Data from the publication's Figure 7b

    10.17182/hepdata.78375.v2/t12

    Pixel-tracklet $p_{T}$ spectrum of observed data in strong channel in the low-Emiss region.

  • Tracklet pT EW SR (fake)

    Data from the publication's Figure 7c

    10.17182/hepdata.78375.v2/t13

    Pixel-tracklet $p_{T}$ spectrum of fake tracklet in electroweak channel in the high-Emiss region.

  • Tracklet pT EW SR (muon)

    Data from the publication's Figure 7c

    10.17182/hepdata.78375.v2/t14

    Pixel-tracklet $p_{T}$ spectrum of muon background in electroweak channel in the high-Emiss region.

  • Tracklet pT EW SR (hadron/electron)

    Data from the publication's Figure 7c

    10.17182/hepdata.78375.v2/t15

    Pixel-tracklet $p_{T}$ spectrum of hadron and electron background in electroweak channel in the high-Emiss region.

  • Tracklet pT EW SR (signal)

    Data from the publication's Figure 7c

    10.17182/hepdata.78375.v2/t16

    Pixel-tracklet $p_{T}$ spectrum of signal ($\tau_{\tilde{\chi}_{1}^{\pm}}$ = 0.2 ns and $m_{\tilde{\chi}_{1}^{\pm}}$ = 400 GeV) in electroweak channel in the high-Emiss...

  • Tracklet pT EW SR (total background)

    Data from the publication's Figure 7c

    10.17182/hepdata.78375.v2/t17

    Pixel-tracklet $p_{T}$ spectrum of total background in electroweak channel in the high-Emiss region.

  • Tracklet pT EW SR (obs)

    Data from the publication's Figure 7c

    10.17182/hepdata.78375.v2/t18

    Pixel-tracklet $p_{T}$ spectrum of observed data in electroweak channel in the high-Emiss region.

  • Tracklet pT Strong SR (fake)

    Data from the publication's Figure 7d

    10.17182/hepdata.78375.v2/t19

    Pixel-tracklet $p_{T}$ spectrum of fake tracklet in strong channel in the high-Emiss region.

  • Tracklet pT Strong SR (muon)

    Data from the publication's Figure 7d

    10.17182/hepdata.78375.v2/t20

    Pixel-tracklet $p_{T}$ spectrum of muon background in strong channel in the high-Emiss region.

  • Tracklet pT Strong SR (hadron/electron)

    Data from the publication's Figure 7d

    10.17182/hepdata.78375.v2/t21

    Pixel-tracklet $p_{T}$ spectrum of hadron and electron background in strong channel in the high-Emiss region.

  • Tracklet pT Strong SR (signal)

    Data from the publication's Figure 7d

    10.17182/hepdata.78375.v2/t22

    Pixel-tracklet $p_{T}$ spectrum of signal ($m_{\tilde{g}}$ = 1600 GeV, $m_{\tilde{\chi}_{1}^{\pm}} = 500 GeV$) in strong channel in the high-Emiss region.

  • Tracklet pT Strong SR (total background)

    Data from the publication's Figure 7d

    10.17182/hepdata.78375.v2/t23

    Pixel-tracklet $p_{T}$ spectrum of total background in strong channel in the high-Emiss region.

  • Tracklet pT Strong SR (obs)

    Data from the publication's Figure 7d

    10.17182/hepdata.78375.v2/t24

    Pixel-tracklet $p_{T}$ spectrum of observed data in strong channel in the high-Emiss region.

  • Exclusion contour EW (exp)

    Data from the publication's Figure 8

    10.17182/hepdata.78375.v2/t25

    Expected exclusion limit at 95% CL obtained in the electroweak production channel in terms of the chargino lifetime ($\tau_{\tilde{\chi}_{1}^{\pm}}$) and...

  • Exclusion contour EW (obs)

    Data from the publication's Figure 8

    10.17182/hepdata.78375.v2/t26

    Observed exclusion limit at 95% CL obtained in the electroweak production channel in terms of the chargino lifetime ($\tau_{\tilde{\chi}_{1}^{\pm}}$) and...

  • Exclusion contour Strong 0.2 ns (exp)

    Data from the publication's Figure 9a

    10.17182/hepdata.78375.v2/t27

    Expected exclusion limit at 95% CL obtained in the strong production channel in terms of the gluino and chargino masses....

  • Exclusion contour Strong 0.2 ns (obs)

    Data from the publication's Figure 9a

    10.17182/hepdata.78375.v2/t28

    Observed exclusion limit at 95% CL obtained in the strong production channel in terms of the gluino and chargino masses....

  • Exclusion contour Strong 1.0 ns (exp)

    Data from the publication's Figure 9b

    10.17182/hepdata.78375.v2/t29

    Expected exclusion limit at 95% CL obtained in the strong production channel in terms of the gluino and chargino masses....

  • Exclusion contour Strong 1.0 ns (obs)

    Data from the publication's Figure 9b

    10.17182/hepdata.78375.v2/t30

    Observed exclusion limit at 95% CL obtained in the strong production channel in terms of the gluino and chargino masses....

  • Exclusion contour EW 2 (exp)

    Data from the publication's Auxiliary figure 1

    10.17182/hepdata.78375.v2/t31

    Expected exclusion limit at 95% CL obtained in the electroweak production channel in terms of the chargino lifetime ($\tau_{\tilde{\chi}_{1}^{\pm}}$) and...

  • Exclusion contour EW 2 (obs)

    Data from the publication's Auxiliary figure 1

    10.17182/hepdata.78375.v2/t32

    Observed exclusion limit at 95% CL obtained in the electroweak production channel in terms of the chargino lifetime ($\tau_{\tilde{\chi}_{1}^{\pm}}$) and...

  • Upper Limit EW

    Data from the publication's Auxiliary figure 1

    10.17182/hepdata.78375.v2/t33

    Model dependent upper limits on cross-section (pb) for the electroweak production are shown by grey numbers in terms of the...

  • Acceptance times Efficiency EW

    Data from the publication's Auxiliary figure 2

    10.17182/hepdata.78375.v2/t34

    Total acceptance $\times$ efficiency of the electroweak channel. The total signal acceptance $\times$ efficiency is defined as the probability of...

  • Acceptance times Efficiency Strong

    Data from the publication's Auxiliary figure 3

    10.17182/hepdata.78375.v2/t35

    Total acceptance $\times$ efficiency of the strong channel. In white regions, no simulation sample is available. The left-upper triangle region...

  • Tracklet Acceptance EW

    Data from the publication's Auxiliary figure 9a

    10.17182/hepdata.78375.v2/t36

    The generator-level acceptance for charginos produced in the electroweak channel as a function of the chargino $eta$ and chargino decay...

  • Tracklet Acceptance times Efficiency EW

    Data from the publication's Auxiliary figure 9b

    10.17182/hepdata.78375.v2/t37

    The acceptance $\times$ efficiency after reconstruction, for selecting and reconstructing charginos produced in the electroweak channel as a function of...

  • Tracklet Acceptance Strong

    Data from the publication's Auxiliary figure 9c

    10.17182/hepdata.78375.v2/t38

    The generator-level acceptance for charginos produced in the strong channel as a function of the chargino $\eta$ and chargino decay...

  • Tracklet Acceptance times Efficiency Strong

    Data from the publication's Auxiliary figure 9d

    10.17182/hepdata.78375.v2/t39

    The acceptance $\times$ efficiency after reconstruction, for selecting and reconstructing charginos produced in the strong channel as a function of...

  • Cutflow EW

    Data from the publication's Table 1

    10.17182/hepdata.78375.v2/t40

    Summary of the selection criteria, and the corresponding observed number of events in data as well as the expected number...

  • Cutflow Strong

    Data from the publication's Table 1

    10.17182/hepdata.78375.v2/t41

    Summary of the selection criteria, and the corresponding observed number of events in data as well as the expected number...

  • Efficiency and Acceptance Table EW

    Data from the publication's Table 2

    10.17182/hepdata.78375.v2/t42

    The event and tracklet generator-level acceptance and selection efficiency for a few electroweak signal models studied in this search. The...

  • Efficiency and Acceptance Table Strong

    Data from the publication's Table 2

    10.17182/hepdata.78375.v2/t43

    The event and tracklet generator-level acceptance and selection efficiency for a few strong signal models studied in this search. The...

  • Signal systematic uncertainties

    Data from the publication's Table 3

    10.17182/hepdata.78375.v2/t44

    Systematic uncertainties in the signal event yields at $m_{\tilde{\chi}_{1}^{\pm}}$ = 400 GeV for the electroweak channel and at $m_{\tilde{g}}$ =...

  • Number in SR

    Data from the publication's Table 4

    10.17182/hepdata.78375.v2/t45

    Observed events, expected background for null signal, and expected signal yields for two benchmark models: electroweak channel with ($m_{\tilde{\chi}_{1}^{\pm}}$, $\tau_{\tilde{\chi}_{1}^{\pm}}$)...

  • Systematic impact

    Data from the publication's Table 5

    10.17182/hepdata.78375.v2/t46

    Effects of systematic uncertainties on the signal exclusion significance at $m_{\tilde{\chi}_{1}^{\pm}}$ = 400 GeV for the electroweak channel and at...

  • Upper Limit Strong

    Data from the publication's Auxiliary table 1

    10.17182/hepdata.78375.v2/t47

    Cross-section upper limits for the strong production, presented in unit of fb. Left-upper triangle region is unphysical because the wino...

Version 2 modifications: Included changes done during the paper submission. The paper was published, and arXiv was updated. List of changes Figaux1 : a unit was corrected, fb -> pb in caption and in the axis label figuaux09 a,b,c,d : caption is modified to explain what each figure shows table 4 caption : anticorrelation -> anti-correlation table 5 caption : tracket -> tracklet fig 8 : the legend for the Run 1 result was changed (added "Obs.")

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