Fitting direct interaction pieces into neutrino puzzles

We develop a framework and unified, compact notation to include neutrino direct interaction effects with neutrino oscillations for a wide class of low-energy, effective four-Fermi interactions. Modest flavor-violating interaction strengths can make significant changes in the boundaries in ΔM2↔sin22θ and in tan2θ13↔tan2θ23 parameter space. We draw examples from the L−R symmetric and MSSM+R/ models and find the recently reported decay-at-rest μ↔e transition probability can be described without oscillations in L−R symmetric models.