Current constraints on squark production scenarios for the excess of high $Q^2$ events at HERA

Abstract

We examine the stop production scenario for the anomalous excess of high $Q^2$ events observed at HERA, by taking into account the constraints coming from the leptoquark search at Tevatron and the atomic parity violation experiments. This scenario is shown to survive persistently even under the severe constraints from the other experiments. In the analysis, the branching ratios $B_{\stp_j}$ of the decay modes $\stp_j\to ed$ $(j=1,2)$ are found to be useful parameters, representing a number of unknown parameters in the SUSY models. By expressing the stop contribution to the cross section of deep inelastic $ep$ scattering $\sigma(ep\to eX)$ in terms of $B_{\stp_1}$ and $B_{\stp_2}$, the allowed region is successfully identified in the parameter space of $B_{\stp_1}$ and $B_{\stp_2}$.