Neutralino Cascades in the (M+1)SSM

Abstract.

In the (M+1)SSM an additional gauge singlet Weyl spinor appears in the neutralino sector. For a large part of the parameter space this approximative eigenstate is the true LSP. Then most sparticle decays proceed via an additional cascade involving the NLSP $\rightarrow$ LSP transition, where the NLSP is the non-singlet next-to-lightest neutralino. We present a comprehensive list of all processes, which contribute to the NLSP $\rightarrow$ LSP transition, the partial widths and the total NLSP decay rate. We perform a scan of the parameters of the model compatible with universal soft terms, and find that the NLSP life time can be quite large, leading to macroscopically displaced vertices. Our results imply that the signatures for sparticle production in the (M+1)SSM can be very different from the MSSM, and are important for calculations of the abundance of dark matter in this model.