Abstract
A search for dark matter particles is performed using events with a Z boson candidate and large missing transverse momentum. The analysis is based on proton–proton collision data at a center-of-mass energy of 13,text {Te}text {V}, collected by the CMS experiment at the LHC in 2016–2018, corresponding to an integrated luminosity of 137,text {fb}^{-1}. The search uses the decay channels {mathrm{Z}} rightarrow {mathrm{e}} {mathrm{e}} and {mathrm{Z}} rightarrow {{upmu }{}{}} {{upmu }{}{}} . No significant excess of events is observed over the background expected from the standard model. Limits are set on dark matter particle production in the context of simplified models with vector, axial-vector, scalar, and pseudoscalar mediators, as well as on a two-Higgs-doublet model with an additional pseudoscalar mediator. In addition, limits are provided for spin-dependent and spin-independent scattering cross sections and are compared to those from direct-detection experiments. The results are also interpreted in the context of models of invisible Higgs boson decays, unparticles, and large extra dimensions.
Highlights
The existence of dark matter (DM) is well established from astrophysical observations [1], where the evidence relies entirely on gravitational interactions
In spite of the abundance of DM, its nature remains unknown. This mystery is the subject of an active experimental program to search for dark matter particles, including direct-detection experiments that search for interactions of ambient DM with ordinary matter, indirect-detection experiments that search for the products of self-annihilation of DM in outer space, and searches at accelerators and colliders that attempt to create DM in the laboratory
The goal of this paper is to explore a set of benchmark models for the production of DM that can contribute to this final state
Summary
The existence of dark matter (DM) is well established from astrophysical observations [1], where the evidence relies entirely on gravitational interactions. We estimate the background contributions using combined information from simulation and control regions (CRs) in data. To enhance the purity of the WZ selection, pTmiss of at least 30 GeV is required and the invariant mass of three leptons is required to be larger than 100 GeV. The backgrounds in this CR are similar to those in the SR, with a sizable nonprompt background from DY events where a jet is misidentified as a lepton [72]. All background estimates for this CR are taken from simulation
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