Dynamical QCD predictions for ultrahigh energy neutrino cross sections

Neutrino-nucleon total cross sections for neutrino energies up to ultrahigh energies (UHE), E-nu = 10(12) GeV, are evaluated within the framework of t he dynamical (radiative) parton model. The expected uncertainties of these predictions do not exceed the level of about 20% at the highest energies wh ere contributions of parton distributions in the yet unmeasured region arou nd x similar or equal to 10(-8) to 10(-9) are non-negligible. This is far m ore accurate than estimated uncertainties of about 2(+/-1) due to fixed pow er law extrapolations of parton distributions to x < 10(-5) required for ca lculating UHE cosmic neutrino event rates. (C) 1999 Elsevier Science B.V. A ll rights reserved.