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 supersymmetry 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 ${\chi }^{-}\text{ra}{\tilde{t}}_R^{\ast }b\text{ra}dsb$ with $m_{{\chi }_1^{-}}\sim 60\text{gev}$ and $m_{\tilde{t}}\sim 52\text{gev}$ leads to signatures very close to the experimental observations.

Comments: 17 pages, submited as uuencoded gz-compressed .tar file containing LATEX file and figures. Some typos fixed and the important error in the caption of Fig. 7 corrected