On Probing theta_{23} in Neutrino Telescopes

TL;DR

This paper explores how measurements of neutrino flux ratios from astrophysical sources at neutrino telescopes can constrain the neutrino mixing angle theta_{23}, especially using neutron sources and combined data.

Contribution

It demonstrates the potential of flux ratio measurements from various astrophysical sources to probe deviations in theta_{23}, including impure source compositions.

Findings

Neutron sources are most sensitive for testing deviations from maximal theta_{23}

Combining flux ratios from the same source improves sensitivity

Using multiple sources enhances the ability to constrain theta_{23}

Abstract

Among all neutrino mixing parameters, the atmospheric neutrino mixing angle theta_{23} introduces the strongest variation on the flux ratios of ultra high energy neutrinos. We investigate the potential of these flux ratio measurements at neutrino telescopes to constrain theta_{23}. We consider astrophysical neutrinos originating from pion, muon-damped and neutron sources and make a comparative study of their sensitivity reach to theta_{23}. It is found that neutron sources are most favorable for testing deviations from maximal theta_{23}. Using a chi^2 analysis, we show in particular the power of combining (i) different flux ratios from the same type of source, and also (ii) combining flux ratios from different astrophysical sources. We include in our analysis ``impure'' sources, i.e., deviations from the usually assumed initial (1 : 2 : 0), (0 : 1 : 0) or (1 : 0 : 0) flux compositions.