On ANITA's sensitivity to long-lived, charged massive particles

We propose that the Antarctic Impulsive Transient Antenna (ANITA) can serve as a detector for long-lived, charged particles, through its measurement of extensive air showers from secondary leptons. To test this on an example model, we simulate the production of staus inside the earth from interactions between ultra-high energy neutrinos and nuclei. We propose that results of ANITA searches for upgoing air showers can be interpreted in terms of constraints on long-lived, charged massive particles (CHAMPs) and consider a supersymmetric partner of the tau lepton, the stau, as an example of such a particle. Exploring the parameter space in stau mass and lifetimes, we find that the stau properties that lead to an observable signal in ANITA are highly energy dependent. At $10^{18.5}$ eV, we find that the best constraints on the product of the neutrino flux and the stau production cross section would be placed near $m_{\tildeτ}=$1 TeV and $τ_{\tildeτ}=$10 ns. Thus ANITA could be sensitive to new physics in a region of parameter space that is unconstrained by experiments at the Large Hadron Collider.