Statistical interpretation of sterile neutrino oscillation searches at reactors

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dc.contributor.authorColoma, Pilaren
dc.contributor.authorHuber, Patricken
dc.contributor.authorSchwetz, Thomasen
dc.contributor.departmentCenter for Neutrino Physicsen
dc.contributor.departmentPhysicsen
dc.date.accessioned2021-06-07T18:37:05Zen
dc.date.available2021-06-07T18:37:05Zen
dc.date.issued2021-01-02en
dc.description.abstractA 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 chi 2-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 sigma level, compared to 3.2 sigma obtained under the assumption that Wilks' theorem applies.en
dc.description.notesThe authors warmly thank Mattias Blennow and Enrique Fernandez-Martinez for useful discussions. PH acknowledges support from the U.S. Department of Energy Office of Science under contract DE-SC0018327. PC acknowledges support from the Grant PROMETEO/2019/083, from the Spanish MICINN through the "Ramon y Cajal" program under Grant RYC2018-024240-I, and from the Spanish Agencia Estatal de Investigacion through Grant "IFT Centro de Excelencia Severo Ochoa SEV-2016-0597". The authors also acknowledge use of the HPC facilities at the IFT (Hydra cluster) and IFIC (SOM cluster). This work was partially supported by the European projects H2020-MSCA-ITN-2015//674896-ELUSIVES and 690575-InvisiblesPlus-H2020-MSCA-RISE-2015.en
dc.description.sponsorshipU.S. Department of Energy Office of ScienceUnited States Department of Energy (DOE) [DE-SC0018327]; Spanish MICINN through the "Ramon y Cajal" program [PROMETEO/2019/083, RYC2018-024240-I]; Spanish Agencia Estatal de Investigacion through Grant "IFT Centro de Excelencia Severo Ochoa" [SEV-2016-0597]; European projects [H2020-MSCA-ITN-2015//674896-ELUSIVES, 690575-InvisiblesPlus-H2020-MSCA-RISE-2015]en
dc.description.versionPublished versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.doihttps://doi.org/10.1140/epjc/s10052-020-08774-2en
dc.identifier.eissn1434-6052en
dc.identifier.issn1434-6044en
dc.identifier.issue1en
dc.identifier.other2en
dc.identifier.urihttp://hdl.handle.net/10919/103660en
dc.identifier.volume81en
dc.language.isoenen
dc.rightsCreative Commons Attribution 4.0 Internationalen
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/en
dc.titleStatistical interpretation of sterile neutrino oscillation searches at reactorsen
dc.title.serialEuropean Physical Journal Cen
dc.typeArticle - Refereeden
dc.type.dcmitypeTexten
dc.type.dcmitypeStillImageen

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