Non-standard neutrino interactions and neutrino oscillation experiments

In analyzing neutrino oscillation experiments it is often assumed that while new physics contributes to neutrino masses, neutrino interactions are given by the Standard Model. We develop a formalism to study new physics effects in neutrino interactions using oscillation experiments. We argue that the notion of branching ratio is not appropriate in this case. We show that a neutrino appearance experiment with sensitivity to oscillation probability P_ij^exp can detect new physics in neutrino interactions if its strength G_N satisfies ( G_N G_F)² ∼ P_ij^exp. Using our formalism we show how current experiments on neutrino oscillation give bounds on the new interactions in various new physics scenarios.