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

Understand

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.