A light stop, with an R-parity-violating coupling $lambda_{131}$, has been suggested as an explanation of the excess in high-$Q^2$ neutral current events observed at the HERA collider. We show that in this scheme a corresponding excess in charged current events --- such as that reported by the H1 Collaboration --- can appear naturally, without calling for the presence of light sleptons or additional R-parity-violating couplings, if there exists a chargino lighter than the stop. The predicted event shapes agree well with the data. The relevant region of parameter space is identified, taking into account constraints coming from precision electroweak measurements, atomic parity violation and recent searches for first-generation leptoquarks at the Tevatron collider.
Download