Excluding Light Gluinos from Z decays

Abstract

We reanalyze the constraints on light gluinos (m_{\tilde{g}}\leq 5 GeV/c^2) from the hadronic Z decays into four jets. We find that the published OPAL data from the 1991 and 1992 runs exclude a light quasi-stable gluino with mass \lesssim 1.5 GeV/c^2 at more than 90% confidence level. This limit depends little on assumptions about the gluino fragmentation and the definition of the gluino mass. The exclusion confidence level is shown as a function of the mass. A future projection is briefly discussed. We also discuss quantitatively how the distributions in the Bengtsson-Zerwas and the modified Nachtmann-Reiter angles change due to the finite bottom quark or gluino mass. The analysis is limited to the leading-order calculations. We, however, give an empirical reason to why the next-to-leading-order corrections are unlikely to change our conclusions.

12 pages, LaTeX, uses psfig, four EPS figures. Discussions on possible NLO corrections expanded. Version to appear in Phys. Lett. B

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• Gauge-mediated SUSY Breaking at an Intermediate Scale
• Light Gluino and the Running of alpha_s
• Constraints on Light Gluinos from Tevatron Dijet Data
• Comments on glueballinos (R0 particles) and R0 searches
• Top Quark Analysis in the Light Gluino Scenario