Enhanced signal of astrophysical tau neutrinos propagating through Earth

Earth absorbs ne and nm of energies above about 100 TeV. As is well known, although nt will also disappear through charged-current interactions, the nt flux will be regenerated by prompt tau decays. We show that this process also produces relatively large fluxes of secondary n̄e and n̄m , greatly enhancing the detectability of the initial nt . This is particularly important because at these energies nt is a significant fraction of the expected astrophysical neutrino flux, and only a tiny portion of the atmospheric neutrino flux.