R-parity violation and the New Events at HERA

Abstract

We summarise possible explanations of the HERA large-Q^2 data, in the framework of R-parity violating supersymmetry. Experimental limits indicate that the most likely production channels are e^+ d --> scharm_L, e^+ d --> stop and e^+ s --> stop. We study the regions of the parameter space that lead to consistent branching ratios, with and without the unification condition for gaugino masses. Cancellations in the coupling of the lightest neutralino to scharm_L, result in a balance between R-parity violating and R-parity conserving decay modes. Such cancellations are not present in the coupling of the neutralino with other particles and an interesting case is sneutrino_L, which could be produced at LEP2 via an L_1L_{2,3}{E}_1^c operator. On the other hand, the stop branching ratios depend mainly on the mass of the lightest chargino and tend to be dominated by either the R-conserving or the R-violating mode.