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

摘要

It is shown that if the charginos decay into very soft leptons or hadrons +$\not{E}$ due to degeneracy/ near- degeneracy with the LSP or the sneutrino,the observability of the recently proposed signal via the single photon (+ softparticles) + $\not{E}$ 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 thesignal, previously computed in the limit $\MSNU \to \infty$ only, isdrastically reduced. We present the formula for the signal cross section in amodel independent way and discuss the observability of the signal at LEP 192and NLC energies.