Search for lightest neutralino and stau pair production in light gravitino scenarios with stau NLSP

TL;DR

This study searches for specific supersymmetric particles, the neutralino and stau, in light gravitino scenarios using DELPHI data, setting new lower mass limits due to no observed evidence of their production.

Contribution

It provides the first experimental mass limits for neutralinos and staus in light gravitino models with the DELPHI detector data.

Findings

Neutralino mass > 71.5 GeV/c^2

Stau mass excluded below 70.0-77.5 GeV/c^2 for certain gravitino masses

Lower stau mass limit of 68.5 GeV/c^2 from combined analyses

Abstract

Promptly decaying lightest neutralinos and long-lived staus are searched for in the context of light gravitino scenarios. It is assumed that the stau is the next to lightest supersymmetric particle (NLSP) and that the lightest neutralino is the next to NLSP (NNLSP). Data collected with the Delphi detector at centre-of-mass energies from 161 to 183 \GeV are analysed. No evidence of the production of these particles is found. Hence, lower mass limits for both kinds of particles are set at 95% C.L.. The mass of gaugino-like neutralinos is found to be greater than 71.5 GeV/c^2. In the search for long-lived stau, masses less than 70.0 to 77.5 \GeVcc are excluded for gravitino masses from 10 to 150 \eVcc . Combining this search with the searches for stable heavy leptons and Minimal Supersymmetric Standard Model staus a lower limit of 68.5 \GeVcc may be set for the stau mass