Current non-conservation effects in ultra-high energy neutrino interactions

The overall hardness scale of the ultra-high energy neutrino-nucleon interactions is usually estimated as $Q^2\sim m_W^2$. The effect of non-conservation of weak currents pushes this scale up to the top quark mass squared and changes dynamics of the scattering process. The Double Leading Log Approximation provides simple and numerically accurate formula for the top-bottom contribution to the total cross section $\sigma^{\nu N}$. Corresponding correction to $\sigma^{\nu N}$ appears to be numerically large. It is comparable with the leading contribution evaluated in the massless quark approximation.