Search for gauge mediated SUSY breaking topologies at $\sqrt{{\mathrm s}} \sim 189$ GeV

Abstract.

Searches for topologies characteristic of Gauge Mediated SUSY Breaking models (GMSB) are performed by analysing 173.6 $\mathrm{pb}^{-1}$ of data collected at $\sqrt s$ = 188.6 GeV with the ALEPH detector. These topologies include acoplanar photons, non-pointing single photon, acoplanar leptons, large impact parameter leptons, detached slepton decay vertices, heavy stable charged sleptons and four leptons plus missing energy final states. No evidence for these new phenomena is observed and limits on production cross sections and sparticle masses are derived. A scan of a minimal GMSB parameter space is performed and model dependent lower limits of about 45 GeV/$c^2$ on the next-to-lightest supersymmetric particle (NLSP) mass and of about 9 TeV on the mass scale parameter $\Lambda$ are derived, independently of the NLSP lifetime.