SEARCHING FOR SUPERSYMMETRY AT e+e− SUPERCOLLIDERS

Abstract

We study the signals resulting from the production and subsequent decays of heavy sleptons, sneutrinos and all the charginos [Formula: see text] and neutralinos [Formula: see text] at ultrahigh energy e+e− colliders. In contrast to existing studies that assume that supersymmetric particles directly decay to the lightest supersymmetric particle (taken here to be the lightest neutralino, [Formula: see text]) which then escapes detection, we incorporate realistic decay patterns using the minimal supersymmetry model as a guide for the masses and mixing angles in the gaugino-Higgsino sector. We show that very heavy sleptons and sneutrinos often decay into heavier charginos and neutralinos which themselves often decay into real W and Z0 bosons and lighter [Formula: see text]'s and [Formula: see text]'s. This results in a considerably softer missing transverse momentum [Formula: see text] spectrum than would be expected if sparticles decayed directly to the [Formula: see text] so that [Formula: see text] is not necessarily a viable signature for very heavy sparticles. We show that the optimal signature for supersymmetry in very high energy e+e− collisions depends on the model parameters. Whereas [Formula: see text] is a viable signature for lighter sleptons and sneutrinos (m ~ 0.3 TeV ), the production of very heavy sparticles is signalled by events with two or more large angle W and Z0 bosons and often a very hard electron. We discuss strategies for extracting the SUSY signal and argue that it can be separated from standard model backgrounds over the whole of parameter space.