Neutrino masses and lepton mixing from A5 and CP

We analyse in details the phenomenological implications for lepton masses and mixing due to the breaking of the discrete symmetries A 5 and CP into the subgroups Z 2 × CP and Z 5 for the neutrino and charged-lepton sectors. The direct product of Z 2 and CP in the neutrino sector allows for a complete determination of masses, mixing and CP phases in terms of only four real parameters. Consequently, we derive accurate analytic expressions for the sum of the neutrino masses as well as the effective Majorana masses, m β and m β β , under different hypotheses for the flavon vevs. Finally, we compare our predictions with the exact numerical results obtained from the diagonalisation of the neutrino mass matrix and discuss their accuracy.