The KTY formalism and nonadiabatic contributions to the neutrino oscillation probability

TL;DR

This paper presents an analytical approach to calculate the effective mixing angle in matter and nonadiabatic contributions to neutrino oscillation probability, useful for long-baseline neutrino experiments.

Contribution

It introduces a method combining the KTY formalism with Landau's approach to analytically evaluate nonadiabatic effects in neutrino oscillations.

Findings

Analytical expression for effective mixing angle in matter.

Explicit formula for nonadiabatic contributions using the formalism.

Application examples demonstrating the method's usefulness.

Abstract

It is shown how to obtain the analytical expression for the effective mixing angle in matter using the formalism which was developed by Kimura, Takamura and Yokomakura. If the baseline of the neutrino path is long enough so that averaging over rapid oscillations is a good approximation, then with the help of Landau's method, the nonadiabatic contribution to the oscillation probability can be expressed analytically by this formalism. We give two examples in which the present method becomes useful.