  Measurements of the solar neutrino mass-squared difference from KamLAND and
solar neutrino data are somewhat discrepant, perhaps due to nonstandard
neutrino interactions in matter. We show that the zenith angle distribution of
solar neutrinos at Hyper-Kamiokande and the energy spectrum of reactor
antineutrinos at JUNO can conclusively confirm the discrepancy and detect new
neutrino interactions.
