ALEPH four jet excess, R_b and R-parity violation

Abstract

We review briefly the indications for some relatively light superpartners based on the R_b anomaly and discuss the dependence of the potential increase in R_b on the assumption about R - parity (non)conservation. We point out that the exotic 4-jet events reported by ALEPH may constitute a signal for super- symmetry with such a light spectrum and with explicitly broken R - parity. A parton level simulation shows that production of a pair of light charginos with their subsequent baryon-number violating decays (either through a stop or through a neutralino) could possibly give rise to this excess. The decay χ^-₁→t^~₁b‾dsb with m_χ^-1~60 GeV and m_t^~~52 GeV leads to signatures very close to the experimental observations.