Long-lived stops in MSSM scenarios with a neutralino LSP

TL;DR

This paper explores the conditions under which long-lived stop squarks could exist in MSSM models with a neutralino LSP, their implications for dark matter, and their detectability at the LHC.

Contribution

It identifies the fine-tuning needed for long-lived stops and analyzes their potential signals at the LHC, linking collider phenomenology with dark matter constraints.

Findings

Long-lived stops require fine-tuned mass degeneracy with the neutralino.

Such stops can produce detectable R-hadrons at the LHC.

Stop-based R-hadrons up to 1 TeV mass could be observed after one year.

Abstract

This work investigates the possibility of a long-lived stop squark in supersymmetric models with the neutralino as the lightest supersymmetric particle (LSP). We study the implications of meta-stable stops on the sparticle mass spectra and the dark matter density. We find that in order to obtain a sufficiently long stop lifetime so as to be observable as a stable R-hadron at an LHC experiment, we need to fine tune the mass degeneracy between the stop and the LSP considerably. This increases the stop-neutralino coanihilation cross section, leaving the neutralino relic density lower than what is expected from the WMAP results for stop masses ~1.5 TeV/c^2. However, if such scenarios are realised in nature we demonstrate that the long-lived stops will be produced at the LHC and that stop-based R-hadrons with masses up to 1 TeV/c^2 can be detected after one year of running at design luminosity.