Regresar

Large-θ<inf>13</inf> perturbation theory of neutrino oscillation for long-baseline experiments

Abstract:

The Cervera et al. formula, the best known approximate formula of neutrino oscillation probability for long-baseline experiments, can be regarded as a second-order perturbative formula with small expansion parameter ε ≡ Δm221/Δm231 ≃ 0.03 under the assumption s13 ≃ εIf θ13 is large, as suggested by a candidate νe event at T2K as well as the recent global analyses, higher order corrections of s13 to the formula would be needed for better accuracy. We compute the corrections systematically by formulating a perturbative framework by taking θ13 as s 13 ∼ √ε ≃ 0.18, which guarantees its validity in a wide range of θ13 below the Chooz limit. We show on general ground that the correction terms must be of order ε2. Yet, they nicely fill the mismatch between the approximate and the exact formulas at low energies and relatively long baselines. General theorems are derived which serve for better understanding of δ-dependence of the oscillation probability. Some interesting implications of the large θ13 hypothesis are discussed. © SISSA 2011.