The neutrino mixing matrix could (almost) be diagonal with entries ±1

It is consistent with the measurement of θ13∼0.15 by Daya Bay to suppose that, in addition to being unitary, the neutrino mixing matrix is also almost Hermitian, and thereby only a small perturbation from diag(+1,−1,−1) in a suitable basis. We suggest this possibility simply as an easily falsifiable ansatz, as well as to offer a potentially useful means of organizing the experimental data. We explore the phenomenological implications of this ansatz and parametrize one type of deviation from the leading order relation |Ve3|≈|Vτ1|. We also emphasize the group-invariant angle between orthogonal matrices as a means of comparing to data. The discussion is purely phenomenological, without any attempt to derive the condition V†≈V from a fundamental theory.