Topologies of the (M+1)SSM with a Singlino LSP at LEP2

TL;DR

The paper investigates collider signatures of the (M+1)SSM with a singlino LSP at LEP2, identifying MSSM-excluded regions and predicting event topologies such as 4-fermion final states with missing energy and possible displaced vertices from a long-lived NLSP. It scans a GUT-scale universal soft-term parameter space, evolves it with RGEs, and computes neutralino mixing and sparticle masses to map observable channels, especially bino decays to the singlino. It finds that small-$\\lambda$ scenarios yield nearly pure singlinos and potentially long-lived NLSPs, enabling displaced-vertex signatures that are not fully covered by MSSM searches. The work underscores the need for dedicated LEP2 efficiency studies for these unconventional topologies and outlines how future colliders could test remaining parameter-space regions through similar cascades and displaced-vertex signals.

Abstract

We study the possible signals of the (M+1)SSM with a singlino LSP at LEP2. First we identify regions of the parameter space which are ruled out by negative results of sparticle searches in the context of the MSSM. In the remaining kinematically accessible regions we present total event rates for topologies which require further studies, i.e. estimations of the corresponding efficiencies: various 4 charged fermion final states with missing energy, possibly with displaced vertices due to a long lifetime of the NLSP, the second lightest neutralino. Searches for these unconventional signatures are essential in order to cover the entire kinematically accessible parameter space of the (M+1)SSM with a singlino LSP at LEP2.