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+ν̄_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 m₄₁²), the mixing matrix element connecting muon flavor to the fourth mass state (|Uμ4|²), and the element connecting tau flavor to the fourth mass state (|Uτ4|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 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\,eV² < Δ m₄₁² <9.6\,eV² , 0.0081 < |Uμ4|² < 0.10 , and |Uτ4|²< 0.035, which narrows the allowed parameter-space for |Uτ4|². However, the primary result of this analysis is the first map of the 3+1 parameter space exploring the interdependence of Δ m₄₁², |Uμ4|², and |Uτ4|².