New results from the DANSS experiment

TL;DR

The DANSS experiment analyzed 3.5 million IBD events at multiple distances from a reactor to search for sterile neutrinos, finding no significant evidence but setting new exclusion limits on sterile neutrino parameters.

Contribution

This study provides new limits on sterile neutrino parameters using a novel analysis of relative IBD rates and spectral shape changes, improving previous constraints.

Findings

No significant sterile neutrino signal detected.

Excluded parameter space up to .008 in .5 region.

Best-fit significance is 1.5c4.

Abstract

We present new preliminary DANSS results based on 3.5 million Inverse Beta Decay (IBD) events collected at 3 distances (10.9 m, 11.9 m, and 12.9 m) from the detector center to the reactor core center. The detector position is changed typically 3 times a week. Therefore many systematic uncertainties are canceled out. A new analysis that uses information about relative IBD counting rates in addition to changes in positron energy spectra shapes is employed. The excluded area covers a very interesting range of the sterile neutrino parameters up to $\sin^2 2\theta_{ee} < 0.008$ in the most sensitive region. No statistically significant evidence for sterile neutrinos is observed. The significance of the best-fit point in the 4$\nu$ case is 1.5$\sigma$