Structure of neutrino mass matrix
  We reconstruct the neutrino mass matrix in the flavor basis, using experimental data on neutrino oscillations. Both normal and inverted hierarchy (ordering) of the mass spectrum are considered. The dependence of the matrix structure on CP violating Majorana phases $\rho$ and $\sigma$ is studied. The results are shown in $\rho-\sigma$ plots. We find the possible matrix structures in the different regions of parameters and discuss the perspectives to further restrict the matrix structure in future experiments. 
Michele Frigerio