Gaugino radiative decay in an anomalous U(1)' model

TL;DR

This paper investigates the radiative decay of neutralinos into axinos and photons within an anomalous U(1)' extension of the MSSM, revealing a high branching ratio in certain parameter regions.

Contribution

It introduces a minimal anomalous U(1)' model where the axino becomes the LSP and calculates the neutralino decay branching ratio, showing significant differences from the CMSSM.

Findings

Branching ratio exceeds 93% in many parameter regions.

Axino is identified as the LSP in this model.

Decay behavior differs markedly from CMSSM predictions.

Abstract

We study the neutralino radiative decay into the lightest supersymmetric particle (LSP) in the framework of a minimal anomalous U(1)' extension of the MSSM. It turns out that in a suitable decoupling limit the axino, which is present in the St\"uckelberg multiplet, is the LSP. We compute the branching ratio (BR) for the decay of a neutralino into an axino and a photon. We find that in a wide region of the parameter space, the BR is higher than 93% in contrast with the typical value (<=1%) in the CMSSM.