Indirect probes of supersymmetry breaking in the JEM-EUSO observatory

Abstract

In this paper we propose indirect probes of the supersymmetry-breaking scale, through observations in the Extreme Universe Space Observatory onboard the Japanese Experiment Module (JEM-EUSO). We consider scenarios where the lightest supersymmetric particle is the gravitino, and the next-to-lightest supersymmetric particle (NLSP) is a long-lived slepton. We demonstrate that JEM-EUSO will be able to probe models where the NLSP decays, therefore probing supersymmetry-breaking scales below $5\ifmmode\times\else\texttimes\fi{}{10}^{6}\text{ }\text{ }\mathrm{GeV}$. The observatory field of view will be large enough to detect a few tens of events per year, depending on its energy threshold. This is complementary to a previous proposal [I. Albuquerque et al., Phys. Rev. Lett. 92, 221802 (2004)] where it was shown that $1\text{ }\text{ }{\mathrm{km}}^{3}$ neutrino telescopes can directly probe this scale. NLSPs will be produced by the interaction of high-energy neutrinos in the Earth. Here we investigate scenarios where they subsequently decay, either in the atmosphere after escaping the Earth or right before leaving the Earth, producing taus. These can be detected by JEM-EUSO and have two distinctive signatures: one, they are produced in the Earth and go upwards in the atmosphere, which allows discrimination from atmospheric taus, and second, as NLSPs are always produced in pairs, coincident taus will be a strong signature for these events. Assuming that the neutrino flux is equivalent to the Waxman-Bahcall limit, we determine the rate of taus from NLSP decays reaching JEM-EUSO's field of view.