Posterior Analysis on IceCube Double Pulse Tau Neutrino Candidates

TL;DR

This paper presents a detailed posterior analysis of tau neutrino candidates in IceCube, focusing on a specific event and exploring the effects of different ice models on signal and background estimations.

Contribution

It introduces a new ice model treatment with nuisance parameters for targeted Monte Carlo re-simulation of tau neutrino events in IceCube.

Findings

Impact of ice model variations on expected neutrino signals

Refined analysis of a key tau neutrino candidate event

Assessment of background neutrino ensemble characteristics

Abstract

The IceCube Neutrino Observatory at the South Pole detects Cherenkov light emitted by charged secondary particles created by primary neutrino interactions. Double pulse waveforms can arise from charged current interactions of astrophysical tau neutrinos with nucleons in the ice and the subsequent decay of tau leptons. The previous 8-year tau double pulse analysis found three tau neutrino candidate events. Among them, the most promising one observed in 2014 is located very near the dust layer in the middle of the detector. A posterior analysis on this event will be presented in this paper, using a new ice model treatment with continuously varying nuisance parameters to do the targeted Monte Carlo re-simulation for tau and other background neutrino ensembles. The impact of different ice models on the expected signal and background statistics will also be discussed.