The search for an additional neutrino mass eigenstate in the 2–100 eV region from ‘Troitsk nu-mass’ data: a detailed analysis

Abstract

In this paper we present the details of our previously published results for a search for an additional neutrino mass state in β-electron spectrum from the Troitsk nu-mass experiment. Here we present steps of the analysis, show a set of likelihood functions obtained for each additional heavy mass value. We demonstrate how systematic errors were estimated. We also compare our results with those published recently for a similar analysis for Mainz data and try to explain why there is a factor of 2-3 difference in the sensitivity for an additional heavy mass. I. INTRODUCTIONRecently we have published a short paper on upper limits on an additional neutrino mass eigenstate in 2 to 100 eV region [1] obtained after reanalysis of our data on the direct electron antineutrino mass measurements in Tritium β-decay in the Troitsk nu-mass experiment [2]. The group led by V. M. Lobashev took these data in the period of 1997-2004. The same file set and the same analysis framework as for the electron anti neutrino mass were used. A search was performed for any sign of an additional neutrino mass state in the β-electron spectrum. Such a state with a finite mass would exhibit itself as a kink in the spectrum. The analysis drew much attention to the fact how data were analyzed, how systematic errors were estimated and why our limits appeared to be by a factor of 2-3 better than those from the similar analysis for Mainz data [3]. Here we present all details of the analysis and make a direct comparison with Mainz results.

First measurements in search for keV sterile neutrino in tritium beta-decay in the Troitsk nu-mass experiment

“…4 as a function of sterile neutrino mass. In the same figure we also present the existing published limits [7][8][9][10][11]. at 95% confidence level.…”

Getting the most neutrinos out of IsoDAR

“…In Ref. [34], the authors used the β decay experiments Mainz [35] and Troitsk [36], fit together with ν e and ν e disappearance data, to derive a 2σ upper bound on the sterile neutrino mass squared splitting of 29 eV 2 .…”

Thresholde−p⟶ nνescattering and the electron neutrino mass

“…A finite neutrino mass would manifest as a depletion of counts, compared to the case of the massless neutrino, in the electron kinetic energy distribution near the endpoint. The latest results for the limit on the electron neutrino mass have been derived over a decade ago from data collected in two eV-precision experiments: at Troitsk (Russia) [1][2][3][4] (m ν < 2.05 eV at 95% c.l.) and Mainz (Germany) [5,6], [7] (m 2 µ = −0.6 ± 2.2(stat) ± 2.1(syst) eV 2 or m ν < 2.3 eV at 95% c.l.).…”