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## Search for an LSP gluino at LEP with the DELPHI detector

### Abstract

In some supersymmetric models, the gluino (\glui) is predicted to be light and stable. In that case, it would hadronize to form R-hadrons. In these models, the missing energy signature of the lightest supersymmetric particle is no longer valid, even if R-parity is conserved. Therefore, such a gluino is not constrained by hadron collider results, which looked for the decay $\glui\to\qqbar\xoi$.\\ Data collected by the DELPHI detector in 1994 at 91.2~GeV have been analysed to search for $\qqbar\glui\glui$ events. No deviation from Standard Model predictions is observed and a gluino mass between 2 and 18~\GeVcc\ is excluded at the 95\% confidence level in these models. Then, R-hadrons produced in the squark decays were searched for in the data collected by DELPHI at the centre-of-mass energies of 189 to 208 GeV, corresponding to an overall integrated luminosity of 609~\pb. The observed number of events is in agreement with the Standard Model predictions. Limits at 95\% confidence level are derived on the squark masses from the excluded regions in the plane (\msqi,\mglui): \begin{itemize} \item[\ ] $\msti 90~\GeVcc$, and $\msbi 96~\GeVcc$ for purely left squarks. \item[\ ] $\msti 87~\GeVcc$, and $\msbi 82~\GeVcc$ independent of the mixing angle

Topics: [PHYS.HEXP] Physics [physics]/High Energy Physics - Experiment [hep-ex]
Publisher: Springer Verlag (Germany)
Year: 2003
OAI identifier: oai:HAL:in2p3-00012365v1
Provided by: Hal-Diderot