Improved eV-scale sterile-neutrino constraints from the second KATRIN measurement campaign

0559786 - ÚJF 2023 RIV US eng J - Journal Article
Aker, M. - Batzler, D. - Beglarian, A. - Behrens, J. - Dragoun, Otokar - Kovalík, Alojz - Lebeda, Ondřej - Ráliš, Jan - Ryšavý, Miloš - Vénos, Drahoslav … Total 130 authors
Improved eV-scale sterile-neutrino constraints from the second KATRIN measurement campaign.
Physical Review D. Roč. 105, č. 7 (2022), č. článku 072004. ISSN 2470-0010. E-ISSN 2470-0029
R&D Projects: GA MŠMT LTT19005
Institutional support: RVO:61389005
Keywords : KATRIN * neutrino
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 5, year: 2022
Method of publishing: Open access
https://doi.org/10.1103/PhysRevD.105.072004

We present the results of the light sterile neutrino search from the second Karlsruhe Tritium Neutrino (KATRIN) measurement campaign in 2019. Approaching nominal activity, 3.76 x 10(6) tritium ss-electrons are analyzed in an energy window extending down to 40 eV below the tritium end point at E-0 = 18.57 keV. We consider the 3 nu + 1 framework with three active and one sterile neutrino flavors. The analysis is sensitive to a fourth mass eigenstate m(4)(2) less than or similar to 1600 eV(2) and active-to-sterile mixing |U-e4|(2) greater than or similar to 6 x 10(-3). As no sterile-neutrino signal was observed, we provide improved exclusion contours on m(4)(2) and |U-e4|(2) at 95% C.L. Our results supersede the limits from the Mainz and Troitsk experiments. Furthermore, we are able to exclude the large Delta m(41)(2) solutions of the reactor antineutrino and gallium anomalies to a great extent. The latter has recently been reaffirmed by the BEST Collaboration and could be explained by a sterile neutrino with large mixing. While the remaining solutions at small Delta m(41)(2) are mostly excluded by short-baseline reactor experiments, KATRIN is the only ongoing laboratory experiment to be sensitive to relevant solutions at large Delta m(41)(2) through a robust spectral shape analysis.
Permanent Link: https://hdl.handle.net/11104/0332987