CP violating phase from charged-lepton mixing

Understand

A model independent analysis of the leptonic Dirac CP-violating phase ({\delta}) is presented.

• The analysis uses the experimentally determined values of the mixing angles in the lepton mixing matrix in order to explore the allowed values for {\delta} and possible general forms for the charged lepton mixing matrix.
• This is done under two general assumptions: 1) that the mixing matrix in the neutrino sector is the so-called tribimaximal matrix and hence the non zero value for {\theta}13 arises due to the mixing matrix in the charged lepton sector and 2) the charged lepton mixing matrix is parametrized in terms of three angles and one phase.
• It is found that any value of {\delta} is still consistent with the data and that, considering the assumptions above, regardless of the value for {\delta}, the 1-3 mixing angle in the charged lepton sector is small but non zero and the 2-3 mixing angle can take values in only two possible small ranges around 0 and {\pi}/2 respectively.