Seminar: Khushboo Dixit - Signatures of Pseudo-Dirac Neutrinos in Astrophysical Neutrino Data from IceCube

Speaker: Khushboo Dixit

Title: Signatures of Pseudo-Dirac Neutrinos in Astrophysical Neutrino Data from IceCube

Abstract

Neutrinos, while often considered as Majorana fermions, can also behave effectively as Dirac fermions, making them candidates for pseudo-Dirac particles. This concept introduces the possibility of oscillations between active and sterile neutrinos, driven by a small mass-squared difference. This phenomenon differs from the standard oscillation scenario involving only the three active neutrino flavors observed across astrophysical distances. In this study, we focus on ana- lyzing publicly available data from the IceCube neutrino observatory, searching for potential pseudo-Dirac signatures in high-energy neutrinos emitted from as- trophysical sources such as NGC 1068, TXS 0506+056 and PKS 1424+240. In the pseudo-Dirac framework, the active neutrino flux from these sources di- minishes due to their oscillation into sterile states. By employing astrophysical flux models, we fit the IceCube data for these sources under both the stan- dard neutrino oscillation framework and the active-sterile oscillation scenario. This enables us to place constraints on the mass-squared difference driving the active-sterile oscillations and the intrinsic source flux. These constraints could be improved by future neutrino observatories such as KM3NeT and IceCube Gen-2.