Direct-transmission models of dynamical supersymmetry breaking

Abstract

We systematically construct gauge-mediated supersymmetry- (SUSY-)breaking models with direct transmission of SUSY-breaking effects to the standard-model sector. We obtain a natural model with the gravitino mass ${m}_{3/2}$ smaller than $1 \mathrm{keV}$ as required from the standard cosmology. If all Yukawa coupling constants are of order one, the SUSY-breaking scale ${m}_{\mathrm{SUSY}}$ transmitted into the standard-model sector is given by ${m}_{\mathrm{SUSY}}\ensuremath{\simeq}0.1({\ensuremath{\alpha}}_{i}/4\ensuremath{\pi})\ensuremath{\Lambda}$ where $\ensuremath{\Lambda}$ is the original dynamical SUSY-breaking scale. Imposing ${m}_{\mathrm{SUSY}}\ensuremath{\simeq}{(10}^{2}$--${10}^{3})$ GeV, we get $\ensuremath{\Lambda}\ensuremath{\simeq}{(10}^{5}--{10}^{6})$ GeV, which yields the gravitino mass ${m}_{3/2}\ensuremath{\simeq}{(10}^{\ensuremath{-}2}$--1) keV.