Sterile Neutrinos and Non-Standard Interactions in Neutrino Telescopes

Sammanfattning: The failure of the Standard Model of particle physics to predict neutrino masses invites us to amend it. We have no reason to believe that the interactions currently described by the gauge group are the whole picture, nor should we expect that the number of fermions hitherto observed is correct. In this thesis, we explore two amendments to the Standard Model, and examine whether either of these is consistent with measured data. Firstly, we consider the sterile neutrino, which has no interactions described by the Standard Model. We examine the effect of this new fermion on the neutrino oscillation probabilities and present what could be a detectable signal in the TeV energy range. Secondly, we consider interactions beyond the Standard Model, possibly stemming from a higher-order theory. We show how the parameters of these Non-Standard Interactions (NSI) can modify the oscillation probabilities and within which energy range we expect to discern this signal. We use data from and simulate event counts in two Cherenkov detectors: IceCube and DeepCore. Moreover, we generate data and simulate a proposed upgrade of the DeepCore detector: PINGU. Using IceCube track events, we obtain best-fit values ∆m^2_41 = 0.01eV^2 and θ_24 = 0.67 for our sterile neutrino hypothesis at a p-value of 20%, which is not statistically significant. Hence, we found no evidence of a sterile neutrino in IceCube data. Moreover, we were unable to distinguish a signal from θ_34 in our IceCube simulation. We obtain stringent bounds on the NSI parameters and compare those to previous results in literature. We show that PINGU is expected to narrow the bound further on ε_μτ , especially by considering a joint analysis with IceCube and DeepCore. Finally, we see that an anti-correlation between ε_eμ and ε_eτ at probability level was propagated down to event level, which we expect to be observable by PINGU.