Tau Neutrinos Favored over Sterile Neutrinos in Atmospheric Muon Neutrino Oscillations

TL;DR

This study analyzes atmospheric neutrino data from Super-Kamiokande, providing evidence that muon neutrinos predominantly oscillate into tau neutrinos rather than sterile neutrinos, with sterile hypotheses rejected at 99% confidence.

Contribution

The paper demonstrates that atmospheric neutrino oscillations are better explained by muon to tau neutrino transitions, ruling out sterile neutrinos with high confidence using multiple data samples.

Findings

No evidence supporting sterile neutrinos in atmospheric oscillations

Muon to tau neutrino oscillation explains all observed data

Sterile neutrino hypothesis rejected at 99% confidence level

Abstract

The previously published atmospheric neutrino data did not distinguish whether muon neutrinos were oscillating into tau neutrinos or sterile neutrinos, as both hypotheses fit the data. Using data recorded in 1100 live-days of the Super-Kamiokande detector, we use three complementary data samples to study the difference in zenith angle distribution due to neutral currents and matter effects. We find no evidence favoring sterile neutrinos, and reject the hypothesis at the 99% confidence level. On the other hand, we find that oscillation between muon and tau neutrinos suffices to explain all the results in hand.