Abstract
A total of 628$\invpb$ of data collected with the ALEPH detector at centre-of-mass energies from 189 to 209 GeV is analysed in the search for gauge mediated SUSY breaking (GMSB) topologies. These topologies include two acoplanar photons, non-pointing single photons, acoplanar leptons, large impact parameter leptons, detached slepton decay vertices, heavy stable charged sleptons and multi-leptons plus missing energy final states. No evidence is found for new phenomena, and lower limits on masses of supersymmetric particles are derived. A scan of a minimal GMSB parameter space is performed and lower limits are set for the next-to-lightest supersymmetric particle (NLSP) mass at 54$\gevcc$ and for the mass scale parameter $\Lambda$ at 10$\tevcc$, independently of the NLSP lifetime. Including the results from the neutral Higgs boson searches, a NLSP mass limit of 77$\gevcc$ is obtained and values of $\Lambda$ up to 16$\tevcc$ are excluded.
Highlights
If supersymmetry (SUSY) were an exact symmetry, the new SUSY particles would be degenerate in mass with their Standard Model (SM) partners
In Gauge Mediated SUSY Breaking (GMSB) models, supersymmetry is broken at a high energy scale in a hidden or “secluded” sector and is propagated down to the visible sector via the SM gauge interactions [1]
The main motivation for GMSB models lies in the fact that they can cope with the experimental absence of flavour changing neutral currents (FCNC)
Summary
If supersymmetry (SUSY) were an exact symmetry, the new SUSY particles would be degenerate in mass with their Standard Model (SM) partners. Assuming R-parity conservation, SUSY particles are pair produced in e+e− collisions and subsequently decay to their SM partner plus gravitinos Another important characteristic of these models is that the next-to-lightest supersymmetric particle (NLSP) is, in general, either the lightest neutralino χ or the sleptons l. The gravitino mass can range from O(10−2) eV/c2 to 1 keV/c2, which practically implies that any NLSP decay length is allowed For this reason topological searches able to identify long-lived or even stable NLSP’s have been developed by the ALEPH collaboration [4, 5, 6]. The sensitivity of these parameters to the different search exclusions is analysed and lower limits on the NLSP mass and the mass scale parameter Λ are derived
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