Heavy neutrino decay at SHALON

TL;DR

This paper reports the detection of five TeV energy air showers from a sub-horizontal direction at SHALON, suggesting decay of a long-lived neutrino-like particle with specific mass and lifetime, possibly linked to anomalies in neutrino experiments.

Contribution

It introduces a novel interpretation of observed air showers as decay products of a long-lived neutrino-like particle, proposing models that connect to existing neutrino anomalies.

Findings

Detected 5 TeV air showers from a sub-horizontal trajectory.

Proposed a neutrino decay model with specific mass and lifetime.

Linked observations to potential explanations for neutrino experiment anomalies.

Abstract

The SHALON Cherenkov telescope has recorded over 2x10^6 extensive air showers during the past 17 years. The analysis of the signal at different zenith angles (\theta) has included observations from the sub-horizontal direction \theta=97^o. This inclination defines an Earth skimming trajectory with 7 km of air and around 1000 km of rock in front of the telescope. During a period of 324 hours of observation, after a cut of shower-like events that may be caused by chaotic sky flashes or reflections on the snow of vertical showers, we have detected 5 air showers of TeV energies. We argue that these events may be caused by the decay of a long-lived penetrating particle entering the atmosphere from the ground and decaying in front of the telescope. We show that this particle can not be a muon or a tau lepton. As a possible explanation, we discuss two scenarios with an unstable neutrino of mass m\approx 0.5 GeV and c\tau\approx 30 m. Remarkably, one of these models has been recently proposed to explain an excess of electron-like neutrino events at MiniBooNE.