St\"uckelino Dark Matter in Anomalous U(1)' Models

TL;DR

This paper investigates the St"uckelino as a dark matter candidate within an anomalous U(1)' extension of the MSSM, analyzing relic density constraints and particle coannihilations to satisfy WMAP observations.

Contribution

It introduces the St"uckelino as a viable LSP dark matter candidate in anomalous U(1)' models and computes relic densities considering coannihilations with near-degenerate particles.

Findings

WMAP relic density constraints can be met with various NLSP and NNLSP configurations.

The viable parameter space exists where the model remains perturbative.

Coannihilations significantly affect the relic density calculations.

Abstract

We study a possible dark matter candidate in the framework of a minimal anomalous $U(1)'$ extension of the MSSM. It turns out that in a suitable decoupling limit the St\"uckelino, the fermionic degree of freedom of the St\"uckelberg multiplet, is the lightest supersymmetric particle (LSP). We compute the relic density of this particle including coannihilations with the next to lightest supersymmetric particle (NLSP) and with the next to next to lightest supersymmetric particle (NNLSP) which are assumed almost degenerate in mass. This assumption is needed in order to satisfy the stringent limits that the Wilkinson Microwave Anisotropy Probe (WMAP) puts on the relic density. We find that the WMAP constraints can be satisifed by different NLSP and NNLSP configurations as a function of the mass gap with the LSP. These results hold in the parameter space region where the model remains perturbative.