New Signature of Squarks

When the gluino is light and long lived, missing energy is a poor signature for both squarks and gluinos. Instead, SqS ∗ q production in ee and pp̄ collisions characteristically results in events with ≥ 4 jets. Methods are proposed for deciding whether an observed excess of 4-jet events is due to SqS ∗ q production. The recent report by ALEPH of observation of 14 4-jet events when 7 were expected is discussed. Dec. 13, 1995; elaborated Dec. 22, 1995 Research supported in part by NSF-PHY-94-23002 I have recently outlined[1, 2, 3, 4] some of the low-energy features of theories in which dimension-3 SUSY breaking operators are highly suppressed. This is the generic situation in several interesting methods of SUSY breaking. Two to four free parameters of the usual minimal supersymmetric standard model (A and the gaugino masses) vanish at tree level. The elimination of these SUSY breaking operators implies that there is no additional CP violation at T=0 beyond what is already present in the standard model[2], avoiding the embarassing SUSY CP problem. Gauginos are massless at tree level but get calculable masses through radiative corrections from electroweak and top-stop loops. Evaluating these leads to gluino and photino masses less than ∼ 1 GeV[1]; the lightest chargino has a mass ≤ mW and thus should be discovered at LEP II. The lightest R-hadron is a gluino-gluon bound state often called R. Its mass should be in the range ∼ 1.2 − 2.2 GeV[5, 2]. It decays to a photino and hadrons. The photino is an attractive dark matter candidate, having the correct abundance for r ≡ m(R)/mγ̃ in the range ∼ 1.6− 2[6], compatible with expectations[1]. For r in this range, τ(R) ∼ (10−10)( Msq 100GeV )sec, so that the lifetime of the R can be long enough that it would not have been detected in existing searches[5]. Methods to study the R and other R-hadrons experimentally are given in [2, 3]. Squarks are pair produced in ee annihilation with cross section 1 2 β times that of a massless quark of the same flavor and chirality. In a hadron collider they can be produced either in pairs from qq̄ annihilation and gluongluon fusion, or singly in association with a gluino or (at the ∼ 1% level) a photino, in quark-gluon fusion. At an ep collider they are produced singly in association with a gluino or (at the 2% level) a photino. Once produced, squarks decay dominantly via Sq → q + g̃. The gluino Although squarks have spin-0, they can be ascribed chirality because supersymmetry associates them with a quark of definite chirality. As discussed below, squark chirality violation is very small in this scenario, except for top-squarks.