Cascade Appearance Signatures of Sterile Neutrinos at 1-100 TeV

TL;DR

This paper investigates the potential of neutrino telescopes, especially IceCube, to detect sterile neutrinos through cascade appearance signatures in the 1-100 TeV energy range, focusing on new channels and existing constraints.

Contribution

It introduces the feasibility of detecting sterile neutrino appearance channels, particularly tau neutrino signatures, at IceCube using ten years of data, expanding beyond traditional muon disappearance searches.

Findings

Tau neutrino appearance signatures are detectable within current constraints.

Sterile neutrino parameters from anomalies are testable at 95% confidence level.

Cascade channels offer promising sensitivity for sterile neutrino detection.

Abstract

Neutrino telescopes provide strong sensitivity to sterile neutrino oscillations through matter-enhanced oscillation, occurring in the few TeV energy range for eV$^{2}$-scale neutrino mass-squared splittings. Prior searches have focused on $\nu_\mu$ disappearance, which has a particularly strong sensitivity to the mixing angle $\theta_{24}$ via $\nu_\mu\rightarrow\nu_s$ transitions. Nowadays, the $\nu_\mu\rightarrow\nu_e$ and $\nu_\mu\rightarrow\nu_\tau$ appearance channels have been considered less promising at neutrino telescopes, due in part to the much smaller target volume for cascades relative to tracks. This work explores the detectability of these signatures at neutrino telescopes given present constraints on sterile neutrino mixing, and as an example, forecasts the sensitivity of the IceCube Neutrino Observatory to the mixing angles $\theta_{14}$, $\theta_{24}$, and $\theta_{34}$ in the 3+1 sterile neutrino model using the cascade channel with ten years of data. We find that $\nu_\tau$ appearance signatures consistent with the existing IceCube $\nu_\mu$ disappearance best-fit point are discoverable for values of $\theta_{34}$ consistent with world constraints, and that the sterile neutrino parameters favored by the BEST and gallium anomalies are expected to be testable at the 95\% confidence level.