  If the Higgs boson weighs about 115 GeV, the effective potential of the
Standard Model becomes unstable above a scale of about 10^6 GeV. This
instability may be rectified only by new bosonic particles such as stop
squarks. However, avoiding the instability requires fine-tuning of the model
couplings, in particular if the theory is not to become non-perturbative before
the Planck scale. Such fine-tuning is automatic in a supersymmetric model, but
is lost if there are no Higgsinos. A light Higgs boson would be prima facie
evidence for supersymmetry in the top-quark and Higgs sectors.
