Ultrahigh-energy neutrino-nucleon deep-inelastic scattering and the Froissart bound.

We present a simple formula for the total cross section σ(νN) of neutral- and charged-current deep-inelastic scattering of ultrahigh-energy neutrinos on isoscalar nuclear targets, which is proportional to the structure function F(2)(νN)(M(V)(2)/s,M(V)(2)), where M(V) is the intermediate-boson mass and s is the square of the center-of-mass energy. The coefficient in front of F(2)(νN)(x,Q(2)) depends on the asymptotic low-x behavior of F(2)(νN). It contains an additional lns term if F(2)(νN) scales with a power of ln(1/x). Hence, an asymptotic low-x behavior F(2)(νN)∝ln(2)(1/x), which is frequently assumed in the literature, already leads to a violation of the Froissart bound on σ(νN).