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

Abstract

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 $g^2$. 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 $g^2=0$, ${\sin }^2(2{\theta }_{24})=0.16$, and $\Delta m_{41}^2=3.5$ eV${}^2$, in agreement with the recent 3+1 sterile neutrino search. Values of $g^2\ge \pi$ are excluded at 95\% confidence level. This result substantially limits decay parameter space indicated by recent global fits, disfavoring the decay scenario.

Comments: 9 pages, 4 figures