1. Improved eV-scale sterile-neutrino constraints from the second KATRIN measurement campaign
- Author
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KATRIN Collaboration, 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., Díaz Barrero, D., 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., Vizcaya Hernández, A. P., 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., AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), KATRIN, and UAM. Departamento de Química Física Aplicada
- Subjects
Antineutrinos ,gallium ,data analysis method ,Physics ,neutrino: mass difference ,shape analysis ,FOS: Physical sciences ,anomaly ,Reactor ,Química ,neutrino: sterile ,KATRIN ,Neutrino Oscillations ,High Energy Physics - Experiment ,High Energy Physics - Experiment (hep-ex) ,tritium: semileptonic decay ,neutrino: flavor ,antineutrino: nuclear reactor ,[PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex] ,spectral ,ddc:530 ,neutrino: mixing ,experimental results - 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
- Published
- 2022