Search for dark matter produced in association with a leptonically decaying Z boson in proton-proton collisions at $\sqrt{s} =$ 13 TeV

TL;DR

This paper reports a search for dark matter produced alongside a Z boson decaying leptonically in proton-proton collisions at 13 TeV, setting limits on various dark matter models and comparing with direct detection experiments.

Contribution

First search for dark matter in association with a Z boson decaying leptonically at 13 TeV, providing new limits on multiple dark matter models and interactions.

Findings

No significant excess observed over standard model background.

Limits set on dark matter production cross sections and mediator models.

Constraints compared with direct detection experiment results.

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 TeV, collected by the CMS experiment at the LHC in 2016-2018, corresponding to an integrated luminosity of 137 fb$^{-1}$. The search uses the decay channels Z $\to$ ee and Z $\to$ $\mu\mu$. 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.