The light gluino mass window revisited

The precise measurements of the “electroweak observables” performed at LEP and SLC are well consistent with the standard model predictions. Deviations from the standard model arising from vacuum polarization diagrams (also called “weak loop corrections”) have been constrained in a model-independent manner with the ε formalism. Within the same formalism, additional deviations from new physics production processes can also be constrained, still in a model-independent way. For instance, a 95% C.L. limit of ΔΓhad<3.9 MeV is set on the partial width of any purely hadronic exotic contribution to Z decays. When applied to the e+e−→qq̄g̃g̃ process, it allows an absolute lower limit to be set on the gluino mass, mg̃>6.3 GeV/c2 at 95% C.L., which definitely closes the so-called light gluino mass window.