Medium effects for terrestrial and atmospheric neutrino oscillations

Matter effects in neutrino propagation translate into effective parameters for the oscillation and fake CP- and CPT-odd quantities, even in a scenario, such as Δ12=0, where no genuine CP violation is present. This fact seems to impose severe restrictions on the determination of intrinsic parameters of the system from long-baseline experiments. We show, however, that the resonance in the effective mixing θ̃13 can be observed for a certain range of baselines. This provides a way to measure the vacuum mixing angle θ13 and the sign of Δm232 from atmospheric neutrinos, using a detector with energy resolution and charge discrimination.