Limiting the Parameter Space for Unstable eV-Scale Neutrinos Using IceCube Data

This Letter extends a recent IceCube sterile neutrino search to include unstable sterile neutrinos within the context of a model termed 3+1+Decay, which expands upon the 3+1 model by introducing sterile neutrino decay to invisible particles with coupling constant g2. The model is attractive since it reduces tension between oscillation experiments within the global fits and with constraints that come from cosmological observables. The analysis uses 10.7 years of up-going muon neutrino data with energy 500 GeV to 100 TeV and with improved reconstruction and modeling of systematics. The best-fit point is found to be g2=0, sin2(2θ24)=0.16, and Δm412=3.5 eV2, in agreement with the recent 3+1 sterile neutrino search. Values of g2≥π are excluded at 95% confidence level. This result substantially limits decay parameter space indicated by recent global fits, disfavoring the decay scenario.