학술논문
Improved eV-scale Sterile-Neutrino Constraints from the Second KATRIN Measurement Campaign
Document Type
Working Paper
Author
Aker, M.; Batzler, D.; Beglarian, A.; Behrens, J.; Berlev, A.; Besserer, U.; Bieringer, B.; Block, F.; Bobien, S.; Bornschein, B.; Bornschein, L.; Böttcher, M.; Brunst, T.; Caldwell, T. S.; Carney, R. M. D.; Chilingaryan, S.; Choi, W.; Debowski, K.; Descher, M.; Barrero, D. Díaz; Doe, P. J.; Dragoun, O.; Drexlin, G.; Edzards, F.; Eitel, K.; Ellinger, E.; Engel, R.; Enomoto, S.; Felden, A.; Formaggio, J. A.; Fränkle, F. M.; Franklin, G. B.; Friedel, F.; Fulst, A.; Gauda, K.; Gavin, A. S.; Gil, W.; Glück, F.; Grössle, R.; Gumbsheimer, R.; Hannen, V.; Haußmann, N.; Helbing, K.; Hickford, S.; Hiller, R.; Hillesheimer, D.; Hinz, D.; Höhn, T.; Houdy, T.; Huber, A.; Jansen, A.; Karl, C.; Kellerer, J.; Kleifges, M.; Klein, M.; Köhler, C.; Köllenberger, L.; Kopmann, A.; Korzeczek, M.; Kovalík, A.; Krasch, B.; Krause, H.; La Cascio, L.; Lasserre, T.; Le, T. L.; Lebeda, O.; Lehnert, B.; Lokhov, A.; Machatschek, M.; Malcherek, E.; Mark, M.; Marsteller, A.; Martin, E. L.; Melzer, C.; Mertens, S.; Mostafa, J.; Müller, K.; Neumann, H.; Niemes, S.; Oelpmann, P.; Parno, D. S.; Poon, A. W. P.; Poyato, J. M. L.; Priester, F.; Ráliš, J.; Ramachandran, S.; Robertson, R. G. H.; Rodejohann, W.; Rodenbeck, C.; Röllig, M.; Röttele, C.; Ryšavý, M.; Sack, R.; Saenz, A.; Salomon, R.; Schäfer, P.; Schimpf, L.; Schlösser, M.; Schlösser, K.; Schlüter, L.; Schneidewind, S.; Schrank, M.; Schwemmer, A.; Šefčík, M.; Sibille, V.; Siegmann, D.; Slezák, M.; Spanier, F.; Steidl, M.; Sturm, M.; Telle, H. H.; Thorne, L. A.; Thümmler, T.; Titov, N.; Tkachev, I.; Urban, K.; Valerius, K.; Vénos, D.; Hernández, A. P. Vizcaya; Weinheimer, C.; Welte, S.; Wendel, J.; Wetter, M.; Wiesinger, C.; Wilkerson, J. F.; Wolf, J.; Wüstling, S.; Wydra, J.; Xu, W.; Zadoroghny, S.; Zeller, G.
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Subject
Language
Abstract
We present the results of the light sterile neutrino search from the second KATRIN measurement campaign in 2019. Approaching nominal activity, $3.76 \times 10^6$ tritium $\beta$-electrons are analyzed in an energy window extending down to $40\,$eV below the tritium endpoint at $E_0 = 18.57\,$keV. We consider the $3\nu+1$ framework with three active and one sterile neutrino flavor. The analysis is sensitive to a fourth mass eigenstate $m_4^2\lesssim1600\,$eV$^2$ and active-to-sterile mixing $|U_{e4}|^2 \gtrsim 6 \times 10^{-3}$. 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.
Comment: 14 pages, 8 figures, 2 tables
Comment: 14 pages, 8 figures, 2 tables