Abstract

A search for new physics in events with two highly Lorentz-boosted Z bosons and large missing transverse momentum is presented. The analyzed proton-proton collision data, corresponding to an integrated luminosity of 137 fb−1, were recorded at sqrt{s} = 13 TeV by the CMS experiment at the CERN LHC. The search utilizes the substructure of jets with large radius to identify quark pairs from Z boson decays. Backgrounds from standard model processes are suppressed by requirements on the jet mass and the missing transverse momentum. No significant excess in the event yield is observed beyond the number of background events expected from the standard model. For a simplified supersymmetric model in which the Z bosons arise from the decay of gluinos, an exclusion limit of 1920 GeV on the gluino mass is set at 95% confidence level. This is the first search for beyond-standard-model production of pairs of boosted Z bosons plus large missing transverse momentum.

Highlights

  • Background estimationThis section focuses on the estimation of SM backgrounds in each pmTiss bin

  • The search described in this paper focuses on gluino decay cascades to Z bosons and the lightest supersymmetric particle (LSP) via the next-to-lightest SUSY particle (NLSP)

  • We evaluate 95% confidence level (CL) upper limits based on the asymptotic form of a likelihood ratio test statistic [80], in conjunction with the CLs criterion described in refs. [81,82,83]

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Summary

The CMS detector and trigger

A detailed description of the CMS detector and the associated coordinate system and kinematic variables is given in ref. [22]. A detailed description of the CMS detector and the associated coordinate system and kinematic variables is given in ref. The core of CMS is a cylindrical superconducting solenoid with an inner diameter of 6 m that provides a 3.8 T axial magnetic field. The detector is nearly hermetic, permitting accurate measurements of pmTiss. The CMS trigger system is described in ref. For this analysis, signal candidate events were recorded by requiring pmTiss at the trigger level to exceed a threshold that varied. Between 100 and 120 GeV, depending on the LHC instantaneous luminosity. Additional triggers based on an isolated lepton or photon are used to select control samples for the background predictions

Simulated event samples
Event reconstruction
Event selection
90 Mass SB
Background estimation method
Background closure in simulation
The pm T iss shape uncertainty
Systematic uncertainties
Results
Summary
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