  This PhD thesis deals with various aspects of (astro)particle physics
phenomenology and consists out of two parts: beyond the Standard Model physics
and neutrino astronomy. In the first part, I focus on beyond the Standard Model
physics at the Large Hadron collider. Concretely, I discuss the interpretation
of a 2015 excess seen by ATLAS in events with jets, missing transverse momentum
and 2 same-flavour, opposite-charge leptons within a model of gauge-mediated
supersymmetry breaking. Our model, which features supersymmetry breaking in
multiple hidden sectors, was able to explain the 2015 data because of the
appearance of an additional massive neutral particle at the bottom of the
spectrum, with couplings dictated by supersymmetry. However, using more recent
data, I show that this specific implementation of the model is now ruled out.
In the second part, I focus on astroparticle physics and neutrino astronomy.
This part consists of two projects. The first and largest of these investigates
the possibility that the neutrinos seen by IceCube are produced by sources
obscured by matter. We show that, in this case, existing bounds from the
extragalactic gamma-ray background can be evaded. In addition, we apply our
model to a set of sources selected for possible obscuration and obtain relevant
bounds on the parameter space. In the final project, I investigate current
constraints on neutrino emission from binary black hole mergers. While no such
neutrinos are typically expected, current constraints are not yet able to rule
out a substantial contribution of such events to the astrophysical neutrino
flux. I show that in the near future, this possibility will be constrained.
Both parts are preceded by an extensive introduction and review of their
respective fields, written to be of general interest.
