Restriction on SUSY Masses from $Z\to hadrons$

Abstract

We remark that the precision of recent determinations of ${\alpha }_s(M_Z^2)$ 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 $\tilde{m}$, we find the bound $\tilde{m}\ge 173$ GeV, at the $2\sigma$ level. At the $2.5\sigma$ level, $\tilde{m}\ge 121$ GeV.

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