Particles, Astrophysics, and Nuclear Physics Seminar

Froissart Bound from Gauge-String Duality:  From Deep Inelastic Scattering to Hadron-Hadron Collision

We begin the process of understanding unitarization in high energy collision at large 't Hooft Coupling, using gauge-string duality (arXiv:0710.4378).  We do so first in the conformal regime, which applies to good accuracy to a number of real and toy problems in QCD.  We consider unitarity and saturation in the conformal regime, noting elastic and absorptive effects, and exploring where graviton and Pomeron dominate.  We also extend the analysis to confining theories.  Though there is important model dependence that requires detailed consideration, the eikonal approximation strongly suggests that the Froissart bound is generically both satisfied and saturated. We find that small-x behavior of the DIS cross sections is consistent with Froissart-like energy dependence at HERA, and we extrapolate this analysis to ultra-high energy neutrino scattering.  Our estimated rates for ultra-high energy neutrino cross section are as much as a factor of 10 smaller than conventional estimates for neutrino energies above 109 GeV, with important implications for experiments searching for extra-galactic neutrinos (arXiv:0708.1960).