The Perturbed Puma Model

The puma model on the basis of the Lorentz and CPT violation may bring an economical interpretation to the conventional neutrinos oscillation and part of the anomalous oscillations. We study the effect of the perturbation to the puma model. In the case of the first-order perturbation which keeps the (23) interchange symmetry, the mixing matrix element U_e3 is always zero. The nonzero mixing matrix element U_e3 is obtained in the second-order perturbation that breaks the (23) interchange symmetry.