Determination of the Atmospheric Neutrino Flux and Searches for New Physics with AMANDA-II

TL;DR

This paper reports on the analysis of atmospheric neutrino data from AMANDA-II, setting limits on new physics phenomena like Lorentz invariance violation and quantum decoherence, while also measuring the atmospheric neutrino flux.

Contribution

It provides the first limits on quantum gravity effects in neutrinos using AMANDA-II data and measures the atmospheric muon neutrino flux above 100 GeV.

Findings

No evidence for Lorentz invariance violation or quantum decoherence.

Set upper limits on VLI and QD parameters.

Measured atmospheric muon neutrino flux above 100 GeV.

Abstract

The AMANDA-II detector, operating since 2000 in the deep ice at the geographic South Pole, has accumulated a large sample of atmospheric muon neutrinos in the 100 GeV to 10 TeV energy range. The zenith angle and energy distribution of these events can be used to search for various phenomenological signatures of quantum gravity in the neutrino sector, such as violation of Lorentz invariance (VLI) or quantum decoherence (QD). Analyzing a set of 5511 candidate neutrino events collected during 1387 days of livetime from 2000 to 2006, we find no evidence for such effects and set upper limits on VLI and QD parameters using a maximum likelihood method. Given the absence of evidence for new flavor-changing physics, we use the same methodology to determine the conventional atmospheric muon neutrino flux above 100 GeV.