# Searching for Dark Matter with $t\overline{t}$ Resonance

## TL;DR

This paper explores the potential of using $tar{t}$ resonance searches at the LHC to detect dark matter models involving a spin-0 mediator, providing new constraints and complementing existing detection methods.

## Contribution

It introduces a novel approach to dark matter searches via $tar{t}$ resonance analysis and sets new limits on mediator and dark matter masses using ATLAS data.

## Key findings

- Mediator masses between 400 and 600 GeV are excluded for certain parameter regions.
- The method provides sensitivity to dark matter models not covered by direct detection experiments.
- Results improve constraints on spin-0 mediator models in collider searches.

## Abstract

Many models containing particles which are candidates for dark matter, assume the standard model particles and the dark matter candidates are mediated by a spin-0 particle. At the LHC, one can use these models for dark matter searches. One of the possible approaches for the search of these models is by considering the decay of the spin-0 particle to a pair of $t\bar{t}$, thus modifying the pattern of the top quark pair invariant mass spectrum. This search suggests a good sensitivity in a parameter space different than the more traditional searches. We examine this sensitivity and put limits on two benchmark models containing candidates for dark matter, using previous ATLAS results. It was found that when the mediator mass ($m_{Y_0}$) and the dark matter candidate mass ($m_{\chi}$) have values of $m_{Y_0} \sim 2 \cdot m_{\chi}$, mediator masses in the range of $[400,600]$ GeV are excluded. We compare our results to direct detection experiments and show that we gain sensitivity for new regions which are not covered by other searches.