Neutrino oscillograms of the Earth and CP violation in neutrino oscillations

Neutrino oscillograms of the Earth are contours of constant oscillation or survival probabilities in the plane of neutrino energy and nadir or zenith angle of neutrino trajectory. They encode information on both the neutrino parameters and the Earth density profile and proved to be a very useful and illuminating tool for analyzing neutrino oscillations in the Earth. The oscillograms exhibit a very rich structure with local and global maxima and minima (including the MSW resonance maxima in the mantle and core of the Earth), saddle points and the parametric enhancement ridges (Fig. 1). It was shown in [1] that all these features can be readily understood in terms of various realizations of just two conditions: the generalized amplitude (collinearity) and phase conditions. The study in [1] was performed in the limit ∆m221 = 0; in the present talk, based on [2], the results for ∆m221 6= 0 are presented.