Physics

Mathematics

Biology

Gene

Neutrino oscillation

Particle physics

Sterile neutrino

Statistics

Paleontology

Neutrino

Nuclear physics

Chemistry

Metallurgy

Materials science

Monte Carlo method

Sigma

Context (archaeology)

Gallium

Quantum mechanics

Biochemistry

Robustness (evolution)

Journal of High Energy Physics

A bstract We evaluate the statistical significance of the 3+1 sterile-neutrino hypothesis using ν e and $$ \overline{\nu} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mover> <mml:mi>ν</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> e disappearance data from reactor, solar and gallium radioactive source experiments. Concerning the latter, we investigate the implications of the recent BEST results. For reactor data we focus on relative measurements independent of flux predictions. For the problem at hand, the usual χ 2 -approximation to hypothesis testing based on Wilks’ theorem has been shown in the literature to be inaccurate. We therefore present results based on Monte Carlo simulations, and find that this typically reduces the significance by roughly 1 σ with respect to the naïve expectation. We find no significant indication in favor of sterile-neutrino oscillations from reactor data. On the other hand, gallium data (dominated by the BEST result) show more than 5 σ of evidence supporting the sterile-neutrino hypothesis, favoring oscillation parameters in agreement with constraints from reactor data. This explanation is, however, in significant tension (∼ 3 σ ) with solar neutrino experiments. In order to assess the robustness of the signal for gallium experiments we present a discussion of the impact of cross-section uncertainties on the results.

Statistical significance of the sterile-neutrino hypothesis in the context of reactor and gallium data