Signatures for squarks in the light gaugino scenario.

When the gluino is light and long lived, missing energy is a poor signature for both squarks and gluinos. Instead, squark pair production leads to events with ≥ 4 jets. If a chargino can decay to squark and quark, missing energy is also a poor signature for the chargino. Properties of 4-jet events originating from squarks are discussed. ALEPH’s preliminary report of an excess of 4-jet events, with a peak in total dijet mass of 109 GeV, is analyzed in terms of SqS ∗ q and chargino pair production. Research supported in part by NSF-PHY-94-23002 Motivations are accumulating for believing the gluino and photino may be light. This is inevitable as long as SUSY-breaking does not arise from gauge singlet vevs and is transmitted to ordinary particles by exchange of very heavy states. In this case gaugino masses and other dimension-3 SUSYbreaking operators are suppressed by a factor M compared to squark masses and other dimension-2 SUSY-breaking operators. This has a number of attractive concomittants: • There is no SUSY CP problem[1]. • Gluino and photino masses are calculable in terms of μ, tanβ, and squark and Higgs masses. Given constraints on these parameters, gluino and photino masses are ≤ O(1) GeV. The mass of the lightest gluino-containing hadron (the gluino-gluon bound state called R) is ∼ 1.3− 2.2 GeV[1]. A chargino is lighter than the W . • With these R and photino masses, the photino relic density is naturally of the correct order of magnitude to account for the dark matter of the universe[3]. • The R lifetime τ(R)> ∼ (10 − 10)( Msq 100GeV ) sec[1] is long enough that it is unlikely to have been detected in existing searches[4]. • An “extra” pseudoscalar is predicted in the flavor singlet meson spectrum at ∼ 1 2 GeV; such a state has been observed[4, 5]. • The ground state R-baryon (udsg̃) may be stable and provide an explanation for cosmic ray events with energies in excess of the GZK bound[6] and anomalous Cygnus X-3 events[1]. In earlier papers I have discussed the phenomenology of light R-hadrons and strategies for detecting them. Here I focus on the modifications of the squark Unless μ∼ few TeV[2].