Cosmic-ray upscattered dark matter and its searches with IceCube

Since its theoretical proposal by Fritz Zwicky in 1933, to account for unseen mass in the Coma cluster of galaxies, dark matter and its gravitational effects have been discovered in several independent astrophysical and cosmological observations. In the past decades, significant progress has been made in both the experimental search and in the theoretical modelling of this new kind of matter. No evidence of non-gravitational interactions of dark matter has been observed so far, despite they are motivated to reproduce its observed abundance in the universe. For this reason, the search for such interactions has rapidly become a growing field of research, and therefore numerous dedicated experiments have been developed. In this thesis, we investigate the use of IceCube and, more generally, of neutrino detectors, as direct detectors of sub-GeV dark matter. The dark matter candidate considered in this work is hadrophilic light dark matter, a new particle that interacts with Standard Model hadrons. Under this assumption, a high-speed component of the galactic dark matter flux arises from its upscattering by cosmic rays, peaking in the GeV energy range. Neutrino telescopes such as IceCube are sensitive to these energies and can therefore be used to place constraints on the parameters of the model, such as the dark matter mass and its coupling to ordinary matter. While similar studies have been conducted with other neutrino experiments, such as Super-Kamiokande, this work represents the first analysis of this type performed with IceCube data. Although this is a first investigation based on public data, we show that competitive results can already be achieved in the relevant parameter space. This confirms the potential of IceCube and other neutrino telescopes in probing sub-GeV dark matter and paves the way for more dedicated analyses in the future.