UHE Neutrinos: Fusing gluons within diffraction cone

Abstract

Currently available estimates of the gluon-fusion effect in ultra-high energy neutrino-nucleon interactions as well as in DIS on protons suffer from uncertainty in defining the scattering profile function $\hat{I}“(b)$. Indeed, the area, $S$, in the impact parameter space populated with interacting gluons varies by a factor of $4-5$ from one analysis to another. To get rid of uncertainties we specify the dipole-nucleon partial-wave amplitude $\hat{I}“(b)$ which meets the restrictions imposed by both the total dipole-nucleon cross section and the small angle elastic scattering amplitude. The area $S$ becomes a well defined quantity proportional to the diffraction cone slope. We solve numerically the non-linear color dipole BFKL equation and evaluate the UHE neutrino-nucleon total cross section. Our finding is that the saturation is a rather weak effect, $\lsim 25%$, up to $E_{\hat{I}}½\sim 10^{12}$ GeV.

6 pages, 2 figures, Talk at the "Low-x" meeting, 2-7 June 2011 Santiago de Compostela