Short-Baseline Electron Neutrino Oscillation Length After Troitsk

Abstract

We discuss the implications for short-baseline electron neutrino disappearance in the 3+1 mixing scheme of the recent Troitsk bounds on the mixing of a neutrino with mass between 2 and 100 eV. Considering the Troitsk data in combination with the results of short-baseline nu_e and antinu_e disappearance experiments, which include the reactor and Gallium anomalies, we derive a 2 sigma allowed range for the effective neutrino squared-mass difference between 0.85 and 43 eV^2. The upper bound implies that it is likely that oscillations in distance and/or energy can be observed in radioactive source experiments. It is also favorable for the ICARUS@CERN experiment, in which it is likely that oscillations are not washed-out in the near detector. We discuss also the implications for neutrinoless double-beta decay.

Figures (3)

• Figure 1: Comparison of the 95% CL allowed region in the $\sin^{2}2\vartheta_{ee}$--$\Delta{m}^{2}_{41}$ plane obtained from the global fit of $\nu_{e}$ and $\bar{\nu}_{e}$ short-baseline oscillation data 1210.5715, the 95% CL bounds obtained from Mainz 1210.4194 and Troitsk 1211.7193 data, and the allowed region obtained from the combined fit. The best-fit points of the oscillation and combined analyses are indicated, respectively, by "$+$" and "$\times$".
• Figure 2: Allowed regions in the $\sin^{2}2\vartheta_{ee}$--$\Delta{m}^{2}_{41}$ plane and marginal $\Delta\chi^{2}$'s for $\sin^{2}2\vartheta_{ee}$ and $\Delta{m}^{2}_{41}$ obtained from the combined fit of $\nu_{e}$ and $\bar{\nu}_{e}$ short-baseline oscillation data and the data of the Mainz 1210.4194 and Troitsk 1211.7193 experiments. The best-fit point is indicated by a "$+$".
• Figure 3: Marginal $\Delta\chi^2$ as a function of $m_{\beta\beta}^{(4)}$ obtained from the fit of $\nu_{e}$ and $\bar{\nu}_{e}$ short-baseline oscillation data (dash-dotted curve), from the combined fit of oscillation and Mainz data (dashed curve), and from the combined fit of oscillation, Mainz and Troitsk data (solid curve). The vertical green band represents the currently most stringent upper bound for $m_{\beta\beta}^{(4)}$ in the no-cancellation case (see text) given by the combined EXO and KamLAND-Zen 90% CL bound on $m_{\beta\beta}$ taking into account nuclear matrix element uncertainties 1211.3863. The vertical dark-green band corresponds to the $1\sigma$ Klapdor-Kleingrothaus et al. range of $m_{\beta\beta}$KlapdorKleingrothaus:2006ff.