Seminar #8: Elena Abad Diaz, "Study of Quasi-Dirac Neutrinos in Solar Experiments"

by Ms Elena Diaz

Wednesday 18 Feb 2026, 10:15 → 11:15 Europe/Zurich

Lecture Hall (1st Wing)

Abstract: Neutrino oscillations provide clear evidence that neutrinos are massive particles, but the nature of their mass term remains unknown. In this work, we study the quasi-Dirac neutrino scenario, in which neutrinos have a dominant Dirac mass with small Majorana contributions, leading to pairs of nearly degenerate mass eigenstates and tiny mass splittings. These splittings introduce oscillations between active and sterile neutrinos, which can modify neutrino oscillation patterns. Solar neutrinos are sensitive to this scenario due to their long propagation distance. We analyze solar neutrino data reported by the Super-Kamiokande and Borexino experiments, comparing quasi-Dirac predictions with current experimental data through a statistical analysis. Our results constrain the mass splittings to be below 10⁻¹¹ eV² and show that current solar neutrino data cannot discriminate between these quasi-Dirac solutions and the standard neutrino oscillation framework. We briefly discuss new approaches to test this scenario.