Extensive air showers from ultrahigh energy gluinos

We study the proposal that the cosmic ray primaries above theGreisen-Zatsepin-Kuzmin (GZK) cutoff are gluino-containing hadrons ($\tildeg$-hadrons). We describe the interaction of $\tilde g$-hadrons with nucleons inthe framework of the Gribov-Regge approach using a modified version of thehadronic interaction model QGSJET for the generations of Extensive Air Showers(EAS). There are two mass windows marginally allowed for gluinos: $m_{\tildeg}\lsim 3$ GeV and $25\lsim m_{\tilde g}\lsim 35$ GeV. Gluino-containinghadrons corresponding to the second window produce EAS very different from theobserved ones. Light $\tilde g$-hadrons corresponding to the first gluinowindow produce EAS similar to those initiated by protons, and only futuredetectors can marginally distinguish them. We propose a beam-dump acceleratorexperiment to search for $\tilde g$-hadrons in this mass window. We emphasizethe importance of this experiment: it can discover (or exclude) the lightgluino and its role as a cosmic ray primary at ultra high energies.Comment: 27 pages latex, 13 eps figure