Excited neutrino production by ultrahigh energy neutrinos traversing the Earth

Abstract

We focus on the production of excited neutrinos by ultra high energy (UHE, ${E}_{\ensuremath{\nu}}>{10}^{4}\text{ }\text{ }\mathrm{GeV}$) neutrinos traversing the Earth. The surviving neutrino fluxes are calculated using the complete system of transport equations for ordinary neutrinos and their excited states, and we compare these results with the obtained using only Standard Model (SM) interactions. We extend the analysis by including the neutral current (NC) and decay regeneration effects, and computing the surviving flux for different values of $f/\ensuremath{\Lambda}$, where $\ensuremath{\Lambda}$ is the compositeness scale and $f$ a coupling factor representing non-perturbative physics. Finally, we analyze the possibilities of detecting such fluxes in a neutrino telescope such as IceCube showing the allowed regions in the $({m}^{*},f/\ensuremath{\Lambda})$ plane for two possible initial fluxes. We have considered the IC80 configuration of IceCube for an operation time of ten years.