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Statistical interpretation of sterile neutrino oscillation searches at reactors

Coloma, Pilar; Huber, Patrick; Schwetz, Thomas ORCID iD icon 1
1 Institut für Astroteilchenphysik (IAP)

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’ theorem, whereby the assumption is made that the log-likelihood is χ2-distributed. However, it is well known that the preconditions for the validity of Wilks’ 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 σ level, compared to 3.2 σ obtained under the assumption that Wilks’ theorem applies.


Verlagsausgabe §
DOI: 10.5445/IR/1000128151
Veröffentlicht am 08.01.2021
Originalveröffentlichung
DOI: 10.1140/epjc/s10052-020-08774-2
Scopus
Zitationen: 15
Web of Science
Zitationen: 13
Dimensions
Zitationen: 16
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Astroteilchenphysik (IAP)
Publikationstyp Zeitschriftenaufsatz
Publikationsmonat/-jahr 01.2021
Sprache Englisch
Identifikator ISSN: 1434-6044, 1434-6052
KITopen-ID: 1000128151
HGF-Programm 51.13.05 (POF IV, LK 01) Theoretische Astroteilchenphysik
Erschienen in The European physical journal / C
Verlag Springer Verlag
Band 81
Heft 1
Seiten Article no.: 2
Bemerkung zur Veröffentlichung Gefördert durch SCOAP3
Vorab online veröffentlicht am 02.01.2021
Nachgewiesen in Scopus
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Web of Science
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