# On the Feasibility of a Stop NLSP in Gravitino Dark Matter Scenarios

## TL;DR

This paper investigates the potential for the lighter stop to be the next-to-lightest supersymmetric particle in gravitino dark matter models, finding limited viable scenarios and analyzing early Universe stop hadron evolution.

## Contribution

It demonstrates the absence of stop NLSP in the CMSSM and identifies small allowed regions in NUHM models, along with analyzing stop hadron cosmology.

## Key findings

- No stop NLSP in CMSSM with universal soft masses.
- Small allowed regions for stop NLSP in NUHM models.
- Most stop hadrons annihilate before affecting Big Bang nucleosynthesis.

## Abstract

We analyze the possibility that the lighter stop {\tilde t_1} could be the next-to-lightest supersymmetric particle (NLSP) in models where the gravitino is the lightest supersymmetric particle (LSP). We do not find any possibility for a stop NLSP in the constrained MSSM with universal input soft supersymmetry-breaking masses at the GUT scale (CMSSM), but do find small allowed regions in models with non-universal Higgs masses (NUHM). We discuss the cosmological evolution of stop hadrons. Most {\tilde t_1}qq `sbaryons' and the corresponding `antisbaryons' annihilate with conventional antibaryons and baryons into {\tilde t_1}{\bar q} `mesinos' and the corresponding `antimesinos', respectively, shortly after the quark-hadron transition in the early Universe, and most mesinos and antimesinos subsequently annihilate. As a result, insufficient metastable charged stop hadrons survive to alter Big Bang nucleosynthesis.