title: TeV strings and the neutrino-nucleon cross section at ultrahigh energies.
abstract: In scenarios with the fundamental unification scale at the TeV one expects string excitations of the standard model fields at accessible energies. We study the neutrino-nucleon cross section in these models. We show that duality of the scattering amplitude forces the existence of a tower of massive leptoquarks that mediate the process in the s channel. Using the narrow-width approximation we find a sum rule for the production rate of resonances with different spin at each mass level. We show that these contributions can increase substantially the standard model neutrino-nucleon cross section, although they seem insufficient to explain the cosmic ray events above the Greisen-Zatsepin-Kuz'min cutoff energy.
authors.affiliation: Departamento de Física Teórica y del Cosmos, Universidad de Granada, E-18071 Granada, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Cornet
authors.forename: J I
authors.initials: JI
authors.lastname: Illana
authors.forename: M
authors.initials: M
authors.lastname: Masip