@Article{Coloma_etal2021,
author="Coloma, P.
and Huber, P.
and Schwetz, T.",
title="Statistical interpretation of sterile neutrino oscillation searches at reactors",
journal="European Physical Journal C",
year="2021",
publisher="Springer",
volume="81",
number="1",
pages="2 - 13pp",
abstract="A considerable experimental effort is currently under way to test the persistent hints for oscillations due to an eV-scale sterile neutrino in the data of various reactor neutrino experiments. The assessment of the statistical significance of these hints is usually based on Wilks{\textquoteright} theorem, whereby the assumption is made that the log-likelihood is chi 2-distributed. However, it is well known that the preconditions for the validity of Wilks{\textquoteright} theorem are not fulfilled for neutrino oscillation experiments. In this work we derive a simple asymptotic form of the actual distribution of the log-likelihood based on reinterpreting the problem as fitting white Gaussian noise. From this formalism we show that, even in the absence of a sterile neutrino, the expectation value for the maximum likelihood estimate of the mixing angle remains non-zero with attendant large values of the log-likelihood. Our analytical results are then confirmed by numerical simulations of a toy reactor experiment. Finally, we apply this framework to the data of the Neutrino-4 experiment and show that the null hypothesis of no-oscillation is rejected at the 2.6 sigma level, compared to 3.2 sigma obtained under the assumption that Wilks{\textquoteright} theorem applies.",
optnote="WOS:000606481000002",
optnote="exported from refbase (https://references.ific.uv.es/refbase/show.php?record=4680), last updated on Wed, 27 Jan 2021 09:17:21 +0000",
issn="1434-6044",
doi="10.1140/epjc/s10052-020-08774-2",
opturl="https://arxiv.org/abs/2008.06083",
opturl="https://doi.org/10.1140/epjc/s10052-020-08774-2",
language="English"
}