14 February 2024

Anirudh Bhatnagar

Title: Probing Quantum-Gravity Decoherence in High-Energy Neutrinos from the Active Galaxy NGC 1068

Abstract: The recent discovery of high-energy neutrinos from an active galactic nuclei; NGC1068, by the IceCube detector marked a significant breakthrough in the field. This discovery has not only opened up an array of new opportunities to probe high-energy neutrino physics but also confirm the first steady-state source of such neutrinos. We exploit the advantages of a stable, continuous source, in contrast to the diffuse flux of neutrinos commonly employed in most experiments. This allows us to discern subtle deviations from standard physics within the energy spectrum of the high-energy neutrinos. In this thesis, we focus on the subtleties introduced by quantum gravity effects in the form of quantum decoherence in the three neutrino framework. These effects are observed through exploring a promising case of neutrino interaction with virtual black holes created in the extreme case of Planck scale fluctuations in space-time. We aim to differentiate between standard and decohered oscillations by effectively bounding the decoherence phase space. We are able to exclude standard oscillations in the decoherence phase space up to a 1 sigma confidence limit, allowing the excluded region to be investigated for measurable effects of quantum gravity in high-energy neutrinos.

Supervisor: Mauricio Bustamante