Neutrino Oscillations and the MSW effect in Random Solar Matter

We investigate the effects of random density fluctuations on neutrino oscillations in the Sun environment. We show how the average of certain quantities which can be used to describe the MSW effect can be computed analytically. We examine also the hypothesis commonly accepted that only perturbations inside the resonance layer can have relevance. The average amplitud, which gives the ''coherent probability'', is computed in an analytical and exact way for the case of colored $\delta$-correlated gaussian noise: the random perturbation induces a renormalization of the matter density which adquires an imaginary part proportional to the fluctuation amplitud at the resonance region. Integral equations are given for the density matrix of the system in the ''optical'' approximation. PACS: 96.60.Kx, 02.50.Ey, 14.60.Pq,95.30.Cq, 96.60.Hv,14.60.Gh.