Signs of pseudo-Dirac neutrinos in SN1987A data
Ivan Martínez-Soler, Yuber F. Perez-Gonzalez, Manibrata Sen
Abstract
Ever since the discovery of neutrinos, we have wondered if neutrinos are their own antiparticles. One remarkable possibility is that neutrinos have a pseudo-Dirac nature, predicting a tiny mass difference between active and sterile states. We analyze the neutrino data from SN1987A in the light of active-sterile oscillations and find a mild preference ($\mathrm{\ensuremath{\Delta}}{\ensuremath{\chi}}^{2}\ensuremath{\approx}3$) for $\ensuremath{\delta}{m}^{2}=6.31\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}20}\text{ }\text{ }{\mathrm{eV}}^{2}$. Notably, the same data is able to exclude $\ensuremath{\delta}{m}^{2}\ensuremath{\sim}[2.55,3.01]\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}20}\text{ }\text{ }{\mathrm{eV}}^{2}$ with $\mathrm{\ensuremath{\Delta}}{\ensuremath{\chi}}^{2}>9$, the tiniest mass differences constrained so far. We further consider the next-generation of experiments and demonstrate their sensitivity exploring the nature of the neutrino mass.