Status of the solution to the solar neutrino problem based on non-standardneutrino interactions

We analyze the current status of the solution to the solar neutrino problem based both on: a) non-standard flavor changing neutrino interactions (FCNI ) and b) non-universal flavor diagonal neutrino interactions (FDNI). We fin d that FCNI and FDNI with matter in the sun as well as in the earth provide a good fit not only to the total rate measured by all solar neutrino exper iments but also to the day-night and seasonal variations of the event rate, as well as the recoil electron energy spectrum measured by the SuperKamiok ande collaboration. This solution does not require massive neutrinos and ne utrino mixing in vacuum. Stringent experimental constraints on FCNI from bo unds on lepton flavor violating decays and on FDNI from limits on lepton un iversality violation rule out nu (e) --> nu (mu) transitions induced by New Physics as a solution to the solar neutrino problem. However, a solution i nvolving nu (e) --> nu (tau) transitions is viable and could be tested inde pendently by the upcoming B-factories if flavor violating tau decays would be observed at a rate close to the present upper bounds.