P. Abreu et al., Search for lightest neutralino and stau pair production in light gravitinoscenarios with stau NLSP, EUR PHY J C, 7(4), 1999, pp. 595-607
Promptly decaying lightest neutralinos and long-lived staus are searched fo
r in the context of light gravitino scenarios. It is assumed that the stau
is the next to lightest supersymmetric particle (NLSP) and that the lightes
t neutralino is the next to NLSP (NNLSP). Data collected with the Delphi de
tector at centre-of-mass energies from 161 to 183 GeV are analysed. No evid
ence of the production of these particles is found. Hence, lower mass limit
s 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 l
ong-lived stau: masses less than 70.0 to 77.5 GeV/c(2) are excluded for gra
vitino masses from 10 to 150 eV/c(2). Combining this search with the search
es for stable heavy leptons and minimal supersymmetric standard model staus
a lower limit of 68.5 GeV/c(2) may be set for the stau mass independent of
the mass of the gravitino.