Search for new phenomena using the invariant mass distribution of same-flavour opposite-sign dilepton pairs in events with missing transverse momentum in $\sqrt{s}=13$ TeV $pp$ collisions with the ATLAS detector

The ATLAS collaboration
No Journal Information, 2018

Abstract (data abstract)
A search for new phenomena in final states containing an $e^+e^-$ or $\mu^+\mu^-$ pair, jets, and large missing transverse momentum is presented. Thisadditional_resources: analysis makes use of proton-proton collision data, collected during 2015 and 2016 at a centre-of-mass energy $\sqrt{s}=13$ TeV with the ATLAS detector at the Large Hadron Collider, which corresponds to an integrated luminosity of 36.1 fb$^{-1}$. The search targets the pair production of supersymmetric coloured particles, squarks or gluinos, and their decays to final states containing an $e^+e^-$ or $\mu^+\mu^-$ pair and the lightest neutralino ($\tilde{\chi}_1^0$) via one of two next-to-lightest neutralino ($\tilde{\chi}_2^0$) decay mechanisms: $\tilde{\chi}_2^0 \rightarrow Z \tilde{\chi}_1^0$, where the $Z$ boson decays leptonically leading to a peak in the dilepton invariant mass distribution around the $Z$ boson mass; and $\tilde{\chi}_2^0 \rightarrow \ell^+\ell^- \tilde{\chi}_1^0$ with no intermediate $\ell^+\ell^-$ resonance, yielding a kinematic endpoint in the dilepton invariant-mass spectrum. The data are found to be consistent with the Standard Model expectation. Results are interpreted using simplified models, and exclude gluinos and squarks with masses as large as 1.85 TeV and 1.3 TeV at 95% confidence level, respectively.

  • SR plot 1

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    Observed and expected dilepton mass distributions, with the bin boundaries considered for the interpretation, in SR-low. All statistical and systematic...

  • SR plot 2

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    Observed and expected dilepton mass distributions, with the bin boundaries considered for the interpretation, in SR-med. All statistical and systematic...

  • SR plot 3

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    Observed and expected dilepton mass distributions, with the bin boundaries considered for the interpretation, in SR-high. All statistical and systematic...

  • SR plot 4

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    Observed and expected dilepton mass distributions, with the bin boundaries considered for the interpretation, in SRC of the low-pT edge...

  • SR plot 5

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    Observed and expected dilepton mass distributions, with the bin boundaries considered for the interpretation, in SRC-MET of the low-pT edge...

  • Exclusion contour 1 (obs.)

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    Observed 95% CL exclusion contours on the gluino and lightest neutralino masses in a SUSY scenario where gluinos are produced...

  • Exclusion contour 1 (exp.)

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    Expected 95% CL exclusion contours on the gluino and lightest neutralino masses in a SUSY scenario where gluinos are produced...

  • Exclusion contour 2 (obs.)

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    Observed 95% CL exclusion contours from the low-p$_{T}$ signal regions on the gluino and lightest neutralino masses in a SUSY...

  • Exclusion contour 2 (exp.)

    10.17182/hepdata.81726.v1/t9

    Expected 95% CL exclusion contours from the low-p$_{T}$ signal regions on the gluino and lightest neutralino masses in a SUSY...

  • Exclusion contour 3 (obs.)

    10.17182/hepdata.81726.v1/t10

    Observed 95% CL exclusion contours on the gluino and lightest neutralino masses in a SUSY scenario where gluinos are produced...

  • Exclusion contour 3 (exp.)

    10.17182/hepdata.81726.v1/t11

    Expected 95% CL exclusion contours on the gluino and lightest neutralino masses in a SUSY scenario where gluinos are produced...

  • Exclusion contour 4 (obs.)

    10.17182/hepdata.81726.v1/t12

    Observed 95% CL exclusion contours from the low-p$_{T}$ signal regions on the gluino and lightest neutralino masses in a SUSY...

  • Exclusion contour 4 (exp.)

    10.17182/hepdata.81726.v1/t13

    Expected 95% CL exclusion contours from the low-p$_{T}$ signal regions on the gluino and lightest neutralino masses in a SUSY...

  • Exclusion contour 5 (obs.)

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    Observed 95% CL exclusion contours from the on-Z signal regions on the gluino and next-to-lightest neutralino masses in a SUSY...

  • Exclusion contour 5 (exp.)

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    Expected 95% CL exclusion contours from the on-Z signal regions on the gluino and next-to-lightest neutralino masses in a SUSY...

  • Exclusion contour 6 (obs.)

    10.17182/hepdata.81726.v1/t16

    Observed 95% CL exclusion contours from the on-Z signal regions on the squark and next-to-lightest neutralino masses in a SUSY...

  • Exclusion contour 6 (exp.)

    10.17182/hepdata.81726.v1/t17

    Expected 95% CL exclusion contours from the on-Z signal regions on the squark and next-to-lightest neutralino masses in a SUSY...

  • Exclusion contour 7 (obs.)

    10.17182/hepdata.81726.v1/t18

    Observed 95% CL exclusion contours from the on-Z signal regions on the gluino and lightest neutralino masses in a SUSY...

  • Exclusion contour 7 (exp.)

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    Expected 95% CL exclusion contours from the on-Z signal regions on the gluino and lightest neutralino masses in a SUSY...

  • Acceptance/Efficiency 1

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    Acceptance and efficiency in the on-Z bin for SR-medium for the SUSY scenario where gluinos are produced in pairs and...

  • Acceptance/Efficiency 2

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    Acceptance and efficiency in the on-Z bin for SR-high for the SUSY scenario where gluinos are produced in pairs and...

  • Acceptance/Efficiency 3

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    Acceptance and efficiency over the full $m_{ll}$ range for SR-low for a SUSY scenario where gluinos are produced in pairs...

  • Acceptance/Efficiency 4

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    Acceptance and efficiency over the full $m_{ll}$ range for SR-medium for a SUSY scenario where gluinos are produced in pairs...

  • Acceptance/Efficiency 5

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    Acceptance and efficiency over the full $m_{ll}$ range for SR-high for a SUSY scenario where gluinos are produced in pairs...

  • Acceptance/Efficiency 6

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    Acceptance and efficiency over the full $m_{ll}$ range for SRC for a SUSY scenario where gluinos are produced in pairs...

  • Acceptance/Efficiency 7

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    Acceptance and efficiency over the full $m_{ll}$ range for SRC-MET for a SUSY scenario where gluinos are produced in pairs...

  • Cross section UL 1

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    The grey numbers show the 95% CL upper limits on the production cross section at each model point, derived from...

  • Cross section UL 2

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    The grey numbers show the 95% CL upper limits on the production cross section at each model point, derived from...

  • Cross section UL 3

    10.17182/hepdata.81726.v1/t29

    The grey numbers show the 95% CL upper limits on the production cross section at each model point, derived from...

  • Cross section UL 4

    10.17182/hepdata.81726.v1/t30

    The grey numbers show the 95% CL upper limits on the production cross section at each model point, derived from...

  • Cross section UL 5

    10.17182/hepdata.81726.v1/t31

    The grey numbers show the 95% CL upper limits on the production cross section at each model point, derived from...

  • Cross section UL 6

    10.17182/hepdata.81726.v1/t32

    The grey numbers show the 95% CL upper limits on the production cross section at each model point, derived from...

  • Cross section UL 7

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    The grey numbers show the 95% CL upper limits on the production cross section at each model point, derived from...

  • Cutflow 1

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    Cutflow table for three benchmark signal points from the SUSY scenario where gluinos are produced in pairs and decay to...

  • Cutflow 2

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    Cutflow table for a signal point from the SUSY scenario where gluinos are produced in pairs and decay via sleptons...

  • Cutflow 3

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    Cutflow table for a signal point from the SUSY scenario where gluinos are produced in pairs and decay to an...

  • Best SR 1

    10.17182/hepdata.81726.v1/t37

    Signal region used to derive the exclusion limit for the SUSY scenario where gluinos are produced in pairs and decay...

  • Best SR 2

    10.17182/hepdata.81726.v1/t38

    Signal region used to derive the exclusion limit for the SUSY scenario where squarks are produced in pairs and decay...

  • Best SR 3

    10.17182/hepdata.81726.v1/t39

    Signal region used to derive the exclusion limit for the SUSY scenario where gluinos are produced in pairs and decay...

  • Best SR 4

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    Signal region used to derive the exclusion limit for the SUSY scenario where gluinos are produced in pairs and decay...

  • Best SR 5

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    Low-$p_{T}$ signal region used to derive the exclusion limit in the compressed region for the SUSY scenario where gluinos are...

  • Best SR 6

    10.17182/hepdata.81726.v1/t42

    Signal region used to derive the exclusion limit for the SUSY scenario where gluinos are produced in pairs and decay...

  • Best SR 7

    10.17182/hepdata.81726.v1/t43

    Low-$p_{T}$ signal region used to derive the exclusion limit for the SUSY scenario where gluinos are produced in pairs and...

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