Abstract
We present the bounds on 3+1 active-sterile neutrino mixing obtained from the first results of the KATRIN experiment. We show that the KATRIN data extend the Mainz and Troitsk bound to smaller values of Delta {m}_{41}^2 for large mixing and improves the exclusion of the large- Delta {m}_{41}^2 solution of the Huber-Muller reactor antineutrino anomaly. We also show that the combined bound of the Mainz, Troitsk, and KATRIN tritium experiments and the Bugey-3, NEOS, PROSPECT, and DANSS reactor spectral ratio measurements exclude most of the region in the (sin22ϑee, Delta {m}_{41}^2 ) plane allowed by the Huber-Muller reactor antineutrino anomaly. Considering two new calculations of the reactor antineutrino fluxes, we show that one, that predicts a lower 235U antineutrino flux, is in agreement with the tritium and reactor spectral ratio measurements, whereas the other leads to a larger tension than the Huber-Muller prediction. We also show that the combined reactor spectral ratio and tritium measurements disfavor the Neutrino-4 indication of large active-sterile mixing. We finally discuss the constraints on the gallium neutrino anomaly.
Highlights
KATRIN data by comparing the results with those of the KATRIN collaboration
We show that the KATRIN data extend the Mainz and Troitsk bound to smaller values of ∆m241 for large mixing and improves the exclusion of the large-∆m241 solution of the Huber-Muller reactor antineutrino anomaly
We show that the combined bound of the Mainz, Troitsk, and KATRIN tritium experiments and the Bugey-3, NEOS, PROSPECT, and DANSS reactor spectral ratio measurements exclude most of the region in the plane allowed by the Huber-Muller reactor antineutrino anomaly
Summary
We present the results of our analysis of the KATRIN data in the standard framework of three-neutrino mixing. We fitted the data considering Asig, Rbg, E0, mβ, |Ue4|2, and m4 as free parameters and we calculated the “free mβ” confidence level contours in the (sin22θee, ∆m241) plane shown in figure 1 marginalizing the χ2 over Asig, Rbg, E0 and mβ This is the most general bound on 3+1 mixing given by the KATRIN data. The combined tritium bound is less stringent than the Mainz+Troitsk bound for ∆m241 ≈ 100 − 600 eV2, where the Mainz+Troitsk bound is dominant
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