Supersymmetric interpretation of high--$Q^2$ HERA events and other related issues

Abstract

In the framework of the minimal supersymmetric standard model (MSSM) with $R-$parity violation, the high--$Q^2$ HERA events can be interpreted as the $s-$channel production of a single stop of $M_{\tilde{t}_1} \approx 200$ GeV, whose dominant decay modes are assumed to be the $R-$parity violating $e^+ + d $ and the $R-$parity conserving $\chi^+ + b$. Assuming only one coupling $\bar{\lambda_{131}^{'}}$ is nonzero of order $\sim 0.04-0.12$, we find that (i) the high$-Q^2$ HERA events can be understood as an $s-$channel stop production with a subsequent decay into $e^+ + (single ~jet)$, and (ii) the ALEPH 4-jet events can be understood in the scenario suggested by Carena et al.. We briefly discuss other physics signals of this scenario at other places such as HERA, LEP200 and Tevatron. The best test for our scenario is to observe the stop decay into $\chi^+ + b$ followed by $\chi^+ \to \tilde{e}^+ + \nu_e $ and $\tilde{e}^+ \to q + \bar{q}^{'}$ via the $R-$parity violating coupling.