# Search for dark matter produced in association with a single top quark or a top quark pair in proton-proton collisions at $\sqrt{s} =$ 13 TeV

## TL;DR

This paper reports a search for dark matter produced alongside top quarks in proton-proton collisions at 13 TeV, including new production modes with a single top quark, but finds no significant deviations from the standard model.

## Contribution

It extends previous searches by including single top quark production modes and combines multiple categories for a comprehensive analysis.

## Key findings

- Excluded scalar mediator masses below 290 GeV.
- Excluded pseudoscalar mediator masses below 300 GeV.
- No significant deviation from standard model predictions.

## Abstract

A search for dark matter produced in association with top quarks in proton-proton collisions at a center-of-mass energy of 13 TeV is presented. The data set used corresponds to an integrated luminosity of 35.9 fb$^{-1}$ recorded with the CMS detector at the LHC. Whereas previous searches for neutral scalar or pseudoscalar mediators considered dark matter production in association with a top quark pair only, this analysis also includes production modes with a single top quark. The results are derived from the combination of multiple selection categories that are defined to target either the single top quark or the top quark pair signature. No significant deviations with respect to the standard model predictions are observed. The results are interpreted in the context of a simplified model in which a scalar or pseudoscalar mediator particle couples to a top quark and subsequently decays into dark matter particles. Scalar and pseudoscalar mediator particles with masses below 290 and 300 GeV, respectively, are excluded at 95% confidence level, assuming a dark matter particle mass of 1 GeV and mediator couplings to fermions and dark matter particles equal to unity.