Search

The ANTARES neutrino telescope and its next-generation successor, KM3NeT, located in the abyss of the Mediterranean Sea, have been designed to study neutrinos from a variety of sources over a wide range of energies and baselines. One of the primary goals of the experiments is to measure the Earth-matter effects stemming from the energy and zenith angle dependence of the atmospheric neutrinos in the multi-GeV range. The study of atmospheric neutrinos is instrumental in addressing some of the outstanding issues in neutrino oscillation physics, especially the fundamental question of the neutrino mass ordering, as well as probing new physics scenarios beyond the Standard Model. In this thesis, we exploit the data of ANTARES and explore the physics potential of KM3NeT-ORCA (ORCA being the low energy component of KM3NeT) to measure the sub-dominant effects in the atmospheric neutrino oscillations vis-\`a-vis non-standard neutrino interactions (NSIs). The Monte Carlo simulation framework, which comprises the simulation of neutrino interactions, particle generation and light propagation, event selection and reconstruction, as well as the statistical treatment of data and systematic uncertainties has been described in great detail. We present a likelihood search for NSIs with 10 years of atmospheric muon-neutrino data recorded with ANTARES and explore sensitivity projections for ORCA based on realistic detector simulations. Moreover, we outline the impact of NSIs on the discovery potential of ORCA towards the neutrino mass ordering. In addition, the sensitivity of ORCA towards the octant of $\theta_{23}$ has been reported. Remarkably, the bounds obtained with ANTARES excludes hitherto allowed regions from current experimental data, and represent the worldwide best limit in the $\mu - \tau$ sector up to date.