Restriction on SUSY Masses from $Z\to hadrons$

Abstract

We remark that the precision of recent determinations of $\alpha_s(M^2_Z)$ is such that one can get bounds on supersymmetric partner masses (squark and gluino) by requiring consistency of determinations of $\alpha_s$ at "low" energies, where those particles do not contribute, and on the $Z$ peak. For approximately degenerate squarks and gluinos with mass $\widetilde{m}$, we find the bound $\widetilde{m}\geq 173$ GeV, at the $2\sigma$ level. At the $2.5\sigma$ level, $\widetilde{m}\geq 121$ GeV.