Large-Theta(13) Perturbation Theory of Neutrino Oscillation

TL;DR

This paper develops a perturbation theory for neutrino oscillations considering a large theta(13), deriving formulas that include matter effects and analyzing their impact on CP violation detection.

Contribution

It introduces a new perturbative framework for neutrino oscillations with large theta(13), accounting for arbitrary matter density profiles.

Findings

Perturbative formula valid to order epsilon^2 derived

Asymmetry in matter density has minimal impact on CP violation detection

Framework applicable to realistic matter density profiles

Abstract

Keeping in mind the possibility of large theta(13), which will be soon explored by reactor and accelerator experiments, I formulate a perturbation theory of neutrino oscillation under the ansatz, sin^2(theta_{13}) \simeq Delta m^2_{21}/\Delta m^2_{31} \simeq 0.03, which is comparable to the Chooz limit. Under the framework, I derive the perturbative formula of the nu_{e} appearance probability valid to order \epsilon^2 in which effects of arbitrary matter density profile is taken into account. I use the formula to analyze problem of possible obstruction to detecting lepton CP violation by effects of asymmetry in matter density profile. Though the asymmetry could be large for neutrino trajectories which traverse both continental and sea crust, its effect on obscuring CP violation measurement is found to be quite small.