Search for the direct production of charginos and neutralinos in $\sqrt{s} = $ 13 TeV $pp$ collisions with the ATLAS detector

The ATLAS collaboration
Eur.Phys.J.C 78 (2018) 154, 2018.

Abstract
A search for the direct production of charginos and neutralinos in final states with at least two hadronically decaying tau leptons is presented. The analysis uses a dataset of $pp$ collisions corresponding to an integrated luminosity of 36.1 fb$^{-1}$, recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 13 TeV. No significant deviation from the Standard Model background expectation is observed. Limits are derived in scenarios of $\tilde{\chi}_{1}^{+}\tilde{\chi}_{1}^{-}$ pair production and of $\tilde{\chi}_{1}^{\pm}\tilde{\chi}_{2}^{0}$ and $\tilde{\chi}_{1}^{+}\tilde{\chi}_{1}^{-}$ production in simplified models where the neutralinos and charginos decay solely via intermediate left-handed staus and tau sneutrinos, and the mass of the $\tilde{\tau}_{\mathrm L}$ state is set to be halfway between the masses of the $\tilde{\chi}_{1}^{\pm}$ and the $\tilde{\chi}_{1}^{0}$. Chargino masses up to 630 GeV are excluded at 95% confidence level in the scenario of direct production of $\tilde{\chi}_{1}^{+}\tilde{\chi}_{1}^{-}$ for a massless $\tilde{\chi}_{1}^{0}$. Common $\tilde{\chi}_{1}^{\pm}$, $\tilde{\chi}_{2}^{0}$ masses up to 760 GeV are excluded in the case of production of $\tilde{\chi}_{1}^{\pm}\tilde{\chi}_{2}^{0}$ and $\tilde{\chi}_{1}^{+}\tilde{\chi}_{1}^{-}$ assuming a massless $\tilde{\chi}_{1}^{0}$. Exclusion limits for additional benchmark scenarios with large and small mass-splitting between the $\tilde{\chi}_{1}^{\pm}$ and the $\tilde{\chi}_{1}^{0}$ are also studied by varying the $\tilde{\tau}_{\mathrm L}$ mass between the masses of the $\tilde{\chi}_{1}^{\pm}$ and the $\tilde{\chi}_{1}^{0}$.

  • CR kinematics 1

    Data from Figure 4a

    10.17182/hepdata.78377.v1/t1

    The $E_{\mathrm T}^{\mathrm{miss}}$ distribution in the $W$-CR region. The SM backgrounds other than multi-jet production are estimated from MC simulation....

  • CR kinematics 2

    Data from Figure 4b

    10.17182/hepdata.78377.v1/t2

    The $m_{\mathrm{T2}}$ distribution in the $W$-CR region. The SM backgrounds other than multi-jet production are estimated from MC simulation. The...

  • VR kinematics 1

    Data from Figure 3a

    10.17182/hepdata.78377.v1/t3

    The $E_{\mathrm T}^{\mathrm{miss}}$ distribution in the multi-jet background VR-F for SR-lowMass. The stacked histograms show the contribution of the non-multi-jet...

  • VR kinematics 2

    Data from Figure 3b

    10.17182/hepdata.78377.v1/t4

    The $m_{\mathrm{T2}}$ distribution in the multi-jet background VR-F for SR-lowMass. The stacked histograms show the contribution of the non-multi-jet SM...

  • VR kinematics 3

    Data from Figure 3c

    10.17182/hepdata.78377.v1/t5

    The $E_{\mathrm T}^{\mathrm{miss}}$ distribution in the multi-jet background VR-F for SR-highMass. The stacked histograms show the contribution of the non-multi-jet...

  • VR kinematics 4

    Data from Figure 3d

    10.17182/hepdata.78377.v1/t6

    The $m_{\mathrm{T2}}$ distribution in the multi-jet background VR-F for SR-highMass. The stacked histograms show the contribution of the non-multi-jet SM...

  • VR kinematics 5

    Data from Figure 4c

    10.17182/hepdata.78377.v1/t7

    The $E_{\mathrm T}^{\mathrm{miss}}$ distribution in the $W$-VR region. The SM backgrounds other than multi-jet production are estimated from MC simulation....

  • VR kinematics 6

    Data from Figure 4d

    10.17182/hepdata.78377.v1/t8

    The $m_{\mathrm{T2}}$ distribution in the $W$-VR region. The SM backgrounds other than multi-jet production are estimated from MC simulation. The...

  • VR kinematics 7

    Data from Figure 5a

    10.17182/hepdata.78377.v1/t9

    The $m_{\mathrm{T2}}$ distribution in the $Z$-VR region. The SM backgrounds other than multi-jet production are estimated from MC simulation. The...

  • VR kinematics 8

    Data from Figure 5b

    10.17182/hepdata.78377.v1/t10

    The $m_{\mathrm{T2}}$ distribution in the Top-VR region. The SM backgrounds other than multi-jet production are estimated from MC simulation. The...

  • VR kinematics 9

    Data from Figure 5c

    10.17182/hepdata.78377.v1/t11

    The $m_{\mathrm{T2}}$ distribution in the $WW$-VR region. The SM backgrounds other than multi-jet production are estimated from MC simulation. The...

  • VR kinematics 10

    Data from Figure 5d

    10.17182/hepdata.78377.v1/t12

    The $m_{\mathrm{T2}}$ distribution in the $ZZ$-VR region. The SM backgrounds other than multi-jet production are estimated from MC simulation. The...

  • N-1 SR kinematics 1

    Data from Figure 6a

    10.17182/hepdata.78377.v1/t13

    The $m_{\mathrm{T2}}$ distribution before the $m_{\mathrm{T2}}$ requirement is applied for SR-lowMass region, where the arrow indicates the position of the...

  • N-1 SR kinematics 2

    Data from Figure 6b

    10.17182/hepdata.78377.v1/t14

    The $m_{\mathrm{T2}}$ distribution before the $m_{\mathrm{T2}}$ requirement is applied for SR-highMass region, where the arrow indicates the position of the...

  • Exclusion contour 1 (obs.)

    Data from Figure 7a

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    Observed exclusion contours in chargino pair production model.

  • Exclusion contour 1 (exp.)

    Data from Figure 7a

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    Expected exclusion contours in chargino pair production model.

  • Exclusion contour 2 (obs.)

    Data from Figure 7b

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    Observed exclusion contours in chargino chargino and chargino neutralino production model.

  • Exclusion contour 2 (exp.)

    Data from Figure 7b

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    Expected exclusion contours in chargino chargino and chargino neutralino production model.

  • X-section U.L. 1

    Data from Figure 8a

    10.17182/hepdata.78377.v1/t19

    Observed upper limits on the model cross-section in units of pb as a function of the chargino and neutralino masses...

  • X-section U.L. 2

    Data from Figure 8b

    10.17182/hepdata.78377.v1/t20

    Observed upper limits on the model cross-section in units of pb as a function of the chargino and neutralino masses...

  • Best SR

    Data from Figure 9

    10.17182/hepdata.78377.v1/t21

    Best signal region used in chargino chargino and chargino neutralino pair production, H is corresponding to SR-highMass and L is...

  • 1D limit 1 (obs.)

    Data from Figure 10a

    10.17182/hepdata.78377.v1/t22

    Observed CLs significance in variable-x model of chargino chargino pair production for compressed mass scenario.

  • 1D limit 1 (exp.)

    Data from Figure 10a

    10.17182/hepdata.78377.v1/t23

    Expected CLs significance in variable-x model of chargino chargino pair production for compressed mass scenario.

  • 1D limit 2 (obs.)

    Data from Figure 10b

    10.17182/hepdata.78377.v1/t24

    Observed CLs significance in variable-x model of chargino chargino pair production for large mass splitting scenario.

  • 1D limit 2 (exp.)

    Data from Figure 10b

    10.17182/hepdata.78377.v1/t25

    Expected CLs significance in variable-x model of chargino chargino pair production for large mass splitting scenario.

  • 1D limit 3 (obs.)

    Data from Figure 10c

    10.17182/hepdata.78377.v1/t26

    Observed CLs significance in variable-x model of chargino chargino and chargino neutralino pair production for compressed mass scenario.

  • 1D limit 3 (exp.)

    Data from Figure 10c

    10.17182/hepdata.78377.v1/t27

    Expected CLs significance in variable-x model of chargino chargino and chargino neutralino pair production for compressed mass scenario.

  • 1D limit 4 (obs.)

    Data from Figure 10d

    10.17182/hepdata.78377.v1/t28

    Observed CLs significance in variable-x model of chargino chargino and chargino neutralino pair production for large mass splitting scenario.

  • 1D limit 4 (exp.)

    Data from Figure 10d

    10.17182/hepdata.78377.v1/t29

    Expected CLs significance in variable-x model of chargino chargino and chargino neutralino pair production for large mass splitting scenario.

  • Acceptance 1

    Data from Figure 13a

    10.17182/hepdata.78377.v1/t30

    Acceptance in SR-lowMass for CHARGINO1 NEUTRALINO2 production.

  • Acceptance 2

    Data from Figure 13c

    10.17182/hepdata.78377.v1/t31

    Acceptance in SR-highMass for CHARGINO1 NEUTRALINO2 production.

  • Acceptance 3

    Data from Figure 13e

    10.17182/hepdata.78377.v1/t32

    Acceptance in SR-highMass for CHARGINO1 CHARGINO1 production.

  • Efficiency 1

    Data from Figure 13b

    10.17182/hepdata.78377.v1/t33

    Efficiency in SR-lowMass for CHARGINO1 NEUTRALINO2 production.

  • Efficiency 2

    Data from Figure 13d

    10.17182/hepdata.78377.v1/t34

    Efficiency in SR-highMass for CHARGINO1 NEUTRALINO2 production.

  • Efficiency 3

    Data from Figure 13f

    10.17182/hepdata.78377.v1/t35

    Efficiency in SR-highMass for CHARGINO1 CHARGINO1 production.

  • Cutflow 1

    Data from Table 10

    10.17182/hepdata.78377.v1/t36

    Cut flow for the reference point 1 (CHARGINO1 NEUTRALINO2 production) in SR-lowMass. The column labelled $N_{raw}$ shows the results for...

  • Cutflow 2

    Data from Table 11

    10.17182/hepdata.78377.v1/t37

    Cut flow for the reference point 2 (CHARGINO1 CHARGINO1 production) in SR-highMass. The column labelled $N_{raw}$ shows the results for...

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