XENONnT -Dominated Solar Neutrinos Constrain the Pseudo-Dirac Splitting
Gio Leone
XENONnT has measured a low-energy solar-neutrino signal dominated by neutrinos. At these energies, an ultra-small pseudo-Dirac mass-squared splitting induces detectable active-sterile oscillations over the Sun--Earth baseline. We study pseudo-Dirac oscillations of the first mass eigenstate, compute the resulting modification of the Be electron-recoil spectrum, and construct a likelihood from the published XENONnT energy spectra. We find that the best fit occurs at zero pseudo-Dirac splitting and rule out values of at , approaching a regime previously discussed for future -sensitive detectors.