On the Oscillation Length Resonance in the Transitions of Solar and Atmospheric Neutrinos Crossing the Earth Core

TL;DR

This paper investigates the conditions under which neutrino flavor transitions are strongly enhanced by oscillation length resonance effects when neutrinos cross the Earth's core, with implications for solar and atmospheric neutrino observations.

Contribution

It provides a detailed analysis of the oscillation length resonance phenomenon in neutrino transitions through the Earth, including for small mixing angles and various transition channels.

Findings

Resonance enhances neutrino flavor transitions crossing the Earth's core.

Resonance also occurs in antineutrino transitions at small mixing angles.

Implications for interpreting solar and atmospheric neutrino experiment results.

Abstract

Assuming two-neutrino mixing takes place in vacuum, we study in detail the conditions under which the $\nu_2 \to \nu_{e}$ and $\nu_{\mu} \to \nu_{e}$ ($\nu_e \to \nu_{\mu(\tau)}$) transitions in the Earth are strongly enhanced by the neutrino oscillation length resonance when the neutrinos cross the Earth core. We show, in particular, that the neutrino oscillation length resonance is operative also in the $\bar{\nu}_{\mu} \to \bar{\nu}_{s}$ transitions at small mixing angles. The properties of the $\nu_2 \to \nu_{e}$ and $\nu_{\mu} \to \nu_{e}$ ($\nu_e \to \nu_{\mu(\tau)}$) transition probabilities in the corresponding resonance regions are examined. Some implications of our results for the transitions of solar and atmospheric neutrinos traversing the Earth core, relevant for the interpretation of the results of the solar and atmospheric neutrino experiments, are also discussed.