Search for Matter-Dependent Atmospheric Neutrino Oscillations in Super-Kamiokande

TL;DR

This study tests matter-dependent neutrino oscillations in Super-Kamiokande data within the MaVaN model, finding no significant evidence for density-dependent effects and supporting standard oscillation models.

Contribution

It provides the first comprehensive analysis of matter-dependent neutrino oscillations using Super-Kamiokande atmospheric data, testing the MaVaN model predictions.

Findings

Density-independent oscillations are favored over matter-dependent models.

No significant difference between best-fit and density-independent cases.

Supports standard neutrino oscillation models over MaVaN predictions.

Abstract

We consider muon neutrino to tau neutrino oscillations in the context of the Mass Varying Neutrino (MaVaN) model, where the neutrino mass can vary depending on the electron density along the flight path of the neutrino. Our analysis assumes a mechanism with dependence only upon the electron density, hence ordinary matter density, of the medium through which the neutrino travels. Fully-contained, partially-contained and upward-going muon atmospheric neutrino data from the Super--Kamiokande detector, taken from the entire SK--I period of 1489 live days, are compared to MaVaN model predictions. We find that, for the case of 2-flavor oscillations, and for the specific models tested, oscillation independent of electron density is favored over density dependence. Assuming maximal mixing, the best-fit case and the density-independent case do not differ significantly.