Revision 2

Accepted · core change · record

Changes against revision 1:

Title: Does an eV-scale sterile neutrino exist?
Plain: A fourth neutrino that feels no force except gravity, with mass near 1 eV, could explain some anomalies. It would show up as extra appearance and disappearance at short distances.
Precise · changed · core: Revision 1: Determine whether a fourth mass state with $\Delta m^2_{41} \sim 0.1 \text{ to } 10\,\mathrm{eV}^2$ and mixings |U_e4|, |U_mu4| large enough to produce sin^2(2 theta_mue) ~ 1e-3 exists. An answer is a $5\,\sigma$ oscillation signal or exclusion of the region preferred by LSND and gallium in both appearance and disappearance.; Revision 2: Determine whether a fourth mass state with $\Delta m^2_{41} \sim 0.1 \text{ to } 10\,\mathrm{eV}^2$ and mixings |U_e4|, |U_mu4| large enough to produce sin^2(2 theta_mue) $\sim 10^{-3}$ exists. An answer is a $5\,\sigma$ oscillation signal or exclusion of the region preferred by LSND and gallium in both appearance and disappearance.
Settled by: Combined SBN-program oscillation fits with near and far detectors, plus reactor (PROSPECT, STEREO) and atmospheric (IceCube) disappearance limits.
Kind: well-posed
Answer type: yes-no
References: (empty)
Literature status: open
Status note: Appearance-disappearance tension in global fits and the 2025 MicroBooNE result disfavor the simple 3+1 model.
Posed since: (empty)

Decisions