New Physics Effects in Long Baseline Experiments

We discuss the implications of new physics, which modifies the matter effect in neutrino oscillations, to long baseline experiments, particularly the MINOS experiment. An analytic formula in the presence of such a new physics interaction is derived for $P({\nu }_{\mu }\to {\nu }_e)$, which is exact in the limit $\mathrm{\Delta }{m}_{21}^2\to 0$.