# Stop Co-Annihilation in the Minimal Supersymmetric Standard Model Revisited

## TL;DR

This paper revisits the stop co-annihilation scenario in the MSSM, analyzing its cosmological implications, direct detection prospects, and collider search strategies, especially considering the Higgs mass constraints.

## Contribution

It provides a detailed re-evaluation of the stop co-annihilation mechanism in the MSSM, focusing on low energy parameters and experimental detectability.

## Key findings

- Direct detection signals are generally below experimental sensitivity.
- LHC searches are essential for probing this scenario.
- Higgs mass constraints influence the viable parameter space.

## Abstract

We re-examine the stop co-annihilation scenario of the Minimal Supersymmetric Standard Model, wherein a bino-like lightest supersymmetric particle has a thermal relic density set by co-annihilations with a scalar partner of the top quark in the early universe. We concentrate on the case where only the top partner sector is relevant for the cosmology, and other particles are heavy. We discuss the cosmology with focus on low energy parameters and an emphasis on the implications of the measured Higgs boson mass and its properties. We find that the irreducible direct detection signal correlated with this cosmology is generically well below projected experimental sensitivity, and in most cases lies below the neutrino background. A larger, detectable, direct detection rate is possible, but is unrelated to the co-annihilation cosmology. LHC searches for compressed spectra are crucial for probing this scenario.