Enhanced signal of astrophysical tau neutrinos propagating through Earth

Abstract

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