High Energy Scattering in Qcd: Dipole Approach with Pomeron Loops

The simplest approach that we can propose for high energy interaction is based 1,2 on the BFKL Pomeron 3 and reggeon-like diagram technique for the BFKL Pomeron interactions . This technique which is a generalization of Gribov Reggeon Calculus , can be written in the elegant form of the functional integral (see Ref. 5 and the next section); and it is a challenge to solve this theory in QCD finding the high energy asymptotic behaviour. However, even this simple approach has not been solved during three decades of attempts by the high energy community. This failure stimulates a search for deeper understanding of physics which is behind the BFKL Pomeron Calculus. In particular, at the end of the Reggeon era it was understood 9,10,11 that the Reggeon Calculus can be reduced to a Markov process 12 for the probability of finding a given number of Pomerons at fixed rapidity Y . Such an interpretation, if it would be reasonable in QCD, can be useful, since it allows us to use powerful methods