A low energy dynamical SUSY breaking scenario motivated from superstring derived unification

Abstract

Recently there has been a resurgence of interest in gauge mediated dynamical supersymmetry breaking scenarios. I investigate how low energy dynamical SUSY breaking may arise from superstring models. In a three generation string derived model I propose that the unbroken hidden non--Abelian gauge group at the string scale is $SU(3)_H$ with matter multiplets. Due to the small gauge content of the hidden gauge group the supersymmetry breaking scale may be consistent with the dynamical SUSY breaking scenarios. The messenger states are obtained in the superstring model from sectors which arise due to the ``Wilson--line'' breaking of the unifying non--Abelian gauge symmetry. An important property of the string motivated messenger states is the absence of superpotential terms with the Standard Model states. The stringy symmetries therefore forbid the flavor changing processes which may arise due to couplings between the messenger sector states and the Standard Model states. Motivated from the problem of string gauge coupling unification I contemplate a scenario in which the messenger sector consists solely of color triplets. This hypothesis predicts a chargino mass below the $W$--boson mass. Imposing the current limits from the LEP1 and LEP1.5 experiments the lightest supersymmetric particles predicted by this hypothesis are in the mass ranges $M_{χ^\pm}\approx55-65$ GeV, $M_{χ^0}\approx35-50$ GeV and $M_{\tildeν}\approx45-60$ GeV which will be tested in the forthcoming LEP2 experiments.