2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/184161The theoretical status of the neutrino-nucleon cross section is reviewed for incident neutrino energies up to E_nu=10^12 GeV, including different approaches to high energy extrapolations. Nonstandard model physics may play a role at ultrahigh energies. The cases of mini-black hole production and electroweak instanton contributions are discussed as examples in the context of ultrahigh energy neutrino scattering.7 pages, 4 figures, to appear in the proceedings of the 21st International Conference on Neutrino Physics and Astrophysics (Neutrino 2004), Paris, France, 14-19 June 2004High Energy Physics - Phenomenologytext