On the Observability of "Invisible" / "Nearly Invisible" Charginos

Abstract

It is shown that if the charginos decay into very soft leptons or hadrons + $/E$ due to degeneracy/ near- degeneracy with the LSP or the sneutrino, the observability of the recently proposed signal via the single photon (+ soft particles) + $/E$ channel crucially depends on the magnitude of the $\SNU$ mass due to destructive interferences in the matrix element squared. If the $\SNU$'s and, consequently, left-sleptons are relatively light, the size of the signal, previously computed in the limit $\MSNU \to \infty$ only, is drastically reduced. We present the formula for the signal cross section in a model independent way and discuss the observability of the signal at LEP 192 and NLC energies.

27 pages, Latex