In the standard model of neutrino oscillations, the neutrino flavor states
are mixtures of mass-eigenstates, and the phenomena are well described by the
neutrino mixing matrix, i.e., the PMNS matrix. I review the recent progress on
parametrization of the neutrino mixing matrix. Besides that I also discuss on
the possibility to describe the neutrino oscillations by a non-standard model
in which the neutrino mixing is caused by the Lorentz violation (LV)
contribution in the effective field theory for LV. We assume that neutrinos are
massless and that neutrino flavor states are mixing states of energy
eigenstates. In our calculation the neutrino mixing parts depend on LV
parameters and neutrino energy. The oscillation amplitude varies with the
neutrino energy, thus neutrino experiments with energy dependence may test and
constrain the Lorentz violation scenario for neutrino oscillation.Comment: 6 pages, Talk presented at CosPA2008, published in Proceedings of the
International Symposium on Cosmology and Particle Astrophysics; Pohang,
Korea, 28 October - 1 November 2008; Editor: Sang Pyo Ki