Problems with Ultrahigh-energy Neutrino Interactions

The IceCube collaboration has recently identified events due to ultrahigh-energy neutrino interactions. Predictions of the neutrino-nucleon cross section at ultrahigh energies require a huge extrapolation of the cross sections experimentally measured at laboratory energies. Upon relating neutrino scattering to deep inelastic electron scattering, we show that the empirically verified color dipole picture is well suited for such an extrapolation. The dominant contribution to the total neutrino-nucleon cross section, even at ultrahigh energies, is due to the kinematic range where color transparency is valid for the color dipole interaction. We deviate from various claims in the literature on the presence of screening effects due to non-linear evolution at ultrahigh neutrino energies.