Day-Night Asymmetries in Active-Sterile Solar Neutrino Oscillations

TL;DR

This paper analyzes how active-sterile neutrino oscillations cause day-night asymmetries in solar neutrino detection, providing analytical formulas and numerical illustrations within a 3+1 neutrino mixing model.

Contribution

It introduces analytical expressions for neutrino flavor transition probabilities in Earth, considering active-sterile mixing and CP phases, applicable to general 3+N_s frameworks.

Findings

Analytical formulas for transition probabilities are derived.

Active-sterile mixing influences day-night asymmetries.

Numerical analysis confirms approximation accuracy in 3+1 model.

Abstract

Day-night asymmetries in active-sterile solar neutrino oscillations are discussed in the general $3+N_{s}$ mixing framework with three active and N_s sterile neutrinos. Analytical expressions of the probability of neutrino flavor transitions in the Earth in the perturbative approximation and in the slab approximation are presented and the effects of active-sterile mixing and of the CP-violating phases are discussed. The accuracy of the analytical approximations and the properties of the day-night asymmetries are illustrated numerically in the 3+1 neutrino mixing framework.