# A Reappraisal on Dark Matter Co-annihilating with a Top/Bottom Partner

## TL;DR

This paper revisits dark matter relic density calculations involving co-annihilation with top or bottom partners, emphasizing the importance of QCD bound-state effects and electroweak processes, and compares predictions with experimental constraints.

## Contribution

It provides a comprehensive framework including bound-state and electroweak effects for co-annihilation scenarios, improving relic density predictions and confronting them with current experimental data.

## Key findings

- Bound-state effects significantly impact relic density calculations.
- LHC and direct detection constraints exclude some parameter regions.
- Electroweak processes are crucial in low mass co-annihilation scenarios.

## Abstract

We revisit the calculation of relic density of dark matter particles co-annihilating with a top or bottom partner, by properly including the QCD bound-states (onia) effects of the colored partners, as well as the relevant electroweak processes which become important in the low mass region. We carefully set up the complete framework that incorporates the relevant contributions and investigate their effects on the cosmologically preferred mass spectrum, which turn out to be comparable in size to those coming from the Sommerfeld enhancement. We apply the calculation to three scenarios: bino-stop and bino-sbottom co-annihilations in supersymmetry, and a vector dark matter co-annihilating with a fermionic top partner. In addition, we confront our analysis of the relic abundance with recent direct detection experiments and collider searches at the LHC, which have important implications in the bino-stop and bino-sbottom scenarios. In particular, in the bino-stop case recent LHC limits have excluded regions of parameter with a direct detection rate that is above the neutrino floor.