Ultrahigh energy neutrino interactions and weak-scale string theories -: art. no. 103006

It has been suggested that ultrahigh energy neutrinos can acquire cross sections approaching hadronic size if the string scale is as low as 1-10 TeV. In this case, the vertical air showers observed with energies above the Greisen-Zatsepin-Kuzmin cutoff at E approximate to 6X10(19) eV could be initiated by neutrinos which are the only known primaries able to travel long distances unimpeded. We have calculated the neutrino-nucleon cross section sigma (KK)(N nu) due to the exchange of Kaluza-Klein excitations of the graviton in a held theoretical framework. We have found that sigma (KK)(N nu) and the transferred energy per interaction are too small to explain vertical showers even in the most optimistic scenario.