SN1987A still shining: A Hint for Pseudo-Dirac Neutrinos


SN1987A still shining: A Hint for Pseudo-Dirac Neutrinos

Ivan Martinez-Soler, Yuber F. Perez-Gonzalez, Manibrata Sen.


Ever since the discovery of neutrinos, one question has daunted us, are neutrinos their own antiparticles? One remarkable possibility is that neutrinos have a pseudo-Dirac nature, truly Majorana neutrinos which behave, for all practical purposes, as Dirac fermions, only distinguishable by tiny mass-squared differences. Such mass differences would induce oscillations that could only be conspicuous over astrophysical baselines. We analyze the neutrino data from SN1987A in the light of these active-sterile oscillations and find a mild preference (\Delta\chi^2\approx 3) for a non-zero quadratic mass difference \delta m^2=6.31\times 10^{-20}~{\rm eV}^2. Notably, the same data is able to exclude \delta m^2\sim [2.55,3.01]\times 10^{-20}~{\rm eV}^2 with \Delta\chi^2> 9, the tiniest mass differences constrained so far. We further consider the future sensitivity of next-generation experiments like the Deep Underground Neutrino Experiment (DUNE) and Hyper-Kamiokande (HK) and demonstrate that, for a future galactic SN occurring at 10~{\rm kpc}, mass-squared differences as small as \sim 10^{-20}~{\rm eV}^2 could be explored.

Associated Fellows