Sterile Neutrino Fits to Short Baseline Neutrino Oscillation Measurements

TL;DR

This paper evaluates short baseline neutrino oscillation data within models involving multiple sterile neutrinos, finding that a (3+3) model provides the best fit but still faces inconsistencies, highlighting the need for further experiments.

Contribution

It introduces and compares (3+1), (3+2), and (3+3) sterile neutrino models, demonstrating the improved fit of the (3+3) model to experimental data.

Findings

(3+3) model achieves 67% goodness of fit.

(3+3) model has 90% compatibility among data sets.

Inconsistencies remain with MiniBooNE low-energy excess.

Abstract

This paper reviews short baseline oscillation experiments as interpreted within the context of one, two, and three sterile neutrino models associated with additional neutrino mass states in the ~1 eV range. Appearance and disappearance signals and limits are considered. We show that fitting short baseline data sets to a (3+3) model, defined by three active and three sterile neutrinos, results in an overall goodness of fit of 67%, and a compatibility of 90% among all data sets -- to be compared to the compatibility of 0.043% and 13% for a (3+1) and a (3+2) model, respectively. While the (3+3) fit yields the highest quality overall, it still finds inconsistencies with the MiniBooNE appearance data sets; in particular, the global fit fails to account for the observed MiniBooNE low-energy excess. Given the overall improvement, we recommend using the results of (3+2) and (3+3) fits, rather than (3+1) fits, for future neutrino oscillation phenomenology. These results motivate the pursuit of further short baseline experiments, such as those reviewed in this paper.