On the IceCube result on ν̄μ →ν̄s oscillations

We elucidate the mechanism of enhancement of the $\bar\nu_\mu \to\bar\nu_s$ transitions at small mixing angles of Earth-core-crossing neutrinos, which is at the basis of the recent result of the IceCube experiment on atmospheric muon anti-neutrino oscillations into sterile anti-neutrino.