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Abstract

In the past decades, many experiments have been built to detect neutrinos and learn about their properties. An example is IceCube, which, with its extraordinary volume, measured a first Glashow resonance (GR) candidate event. In the first part of this thesis, we utilize the GR to infer astrophysical neutrino sources since it is an excellent probe to distinguish between neutrinos and antineutrinos. Assuming that the production is dominated by the Δ-resonance, we can exclude the μ-damped pγ source at about 2σ confidence level. Moreover, we perform a projection for IceCube- Gen2. While the GR is a process that can happen within the Standard Model, it can be sensitive to new physics as well. One such new physics model is discussed in the context of neutrinoless double beta decay (0νββ). We propose a complex scalar that carries two units of lepton number and argue that its capture can induce a signal that is indistinguishable from standard 0νββ. For this, we do not require a Majorana neutrino mass or lepton number violation in the zero-density vacuum Lagrangian and thus we can circumvent the famous Schechter-Valle theorem. We also discuss the influence that such a scalar would have on measurements of the GR.