Perspectives for Detection of a Higgsino-like Relic Neutralino

Abstract

It has been conjectured by Ambrosanio, Kane, Kribs, Martin and Mrenna (AKM) that the CDF event $p \bar p \to e^+ e^- \gamma \gamma + missing E_T$ is due to a decay chain involving two neutralino states (the lightest and the next-to-lightest ones). The lightest neutralino ($\chi_{AKM}$) has been further considered by Kane and Wells as a candidate for cold dark matter. In this paper we examine the properties of relic $\chi_{AKM}$'s in their full parameter space, and examine the perspectives for detection by comparing theoretical predictions to sensitivities of various experimental searches. We find that for most regions of the parameter space the detectability of a relic $\chi_{AKM}$ would require quite substantial improvements in current experimental sensitivities. The measurements of neutrino fluxes from the center of the Earth and of an excess of $\bar{p}/p$ in cosmic rays are shown to offer some favorable perspectives for investigating a region of the $\chi_{AKM}$ parameter space around the maximal $\tan \beta$ value allowed by the model.