QCD Color Glass Condensate Model in Warped Brane Models

Abstract

Hadron-hadron interaction and Deep Inelastic Scattering (DIS) at very high energies is dominated by events at small-$x_B$ regime. Interesting and complex physical content of this regime is described by a phenomenological model called McLerran-Venugopalan Color Glass Condensate (MVCGC) model. The advantage of this formalism is the existence of a renormalization-type equation which relates directly observable low energy (small-$x_B$) physics to high energy scales where one expects the appearance of phenomena beyond Standard model. After a brief argument about complexity of observations and their interpretation, we extend CGC to warped space-times with brane boundaries and show that in a hadron-hadron collision or DIS all the events - and not just hard processes - have an extended particle distribution in the bulk. In other word, particles living on the visible brane escape to the bulk. For an observer on the brane the phenomenon should appear as time decoherence in the outgoing particles or missing energy, depending on the time particles propagate in the bulk before coming back to the brane. Assuming that primaries of UHECRs are nucleons, the interaction of Ultra High Energy Cosmic Rays (UHECRs) in the terrestrial atmosphere is the most energetic hadron-hadron interaction available for observation. Using the prediction of CGC for gluon distribution as well as classical propagation of relativistic particles in the bulk, we constrain the parameter space of warped brane models.