Exploration of mass splitting and muon/tau mixing parameters for an eV-scale sterile neutrino with IceCube.

We present the first three-parameter fit to a 3+1 sterile neutrino model using 7.634 years of data from the IceCube Neutrino Observatory on ν μ + ν ‾ μ charged-current interactions in the energy range 500–9976 GeV. Our analysis is sensitive to the mass-squared splitting between the heaviest and lightest mass state (Δ m 41 2), the mixing matrix element connecting muon flavor to the fourth mass state (| U μ 4 | 2), and the element connecting tau flavor to the fourth mass state (| U τ 4 | 2). Predicted propagation effects in matter enhance the signature through a resonance as atmospheric neutrinos from the Northern Hemisphere traverse the Earth to the IceCube detector at the South Pole. The remaining sterile neutrino matrix elements are left fixed, with | U e 4 | 2 = 0 and δ 14 = 0 , as they have a negligible effect, and δ 24 = π is set to give the most conservative limits. The result is consistent with the no-sterile neutrino hypothesis with a probability of 4.3%. Profiling the likelihood of each parameter yields the 90% confidence levels: 2.4 eV 2 < Δ m 41 2 < 9.6 eV 2 , 0.0081 < | U μ 4 | 2 < 0.10 , and | U τ 4 | 2 < 0.035 , which narrows the allowed parameter-space for | U τ 4 | 2. However, the primary result of this analysis is the first map of the 3+1 parameter space exploring the interdependence of Δ m 41 2 , | U μ 4 | 2 , and | U τ 4 | 2. [ABSTRACT FROM AUTHOR]

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