QCD at high energy: saturation and fluctuation effects
Abstract
Description
In these proceedings, I shall review the basic concepts of perturbative QCD in its high-energy limit. I shall concentrate on the approach to the unitarity limit, usually referred to as saturation, as well as on the gluon-number fluctuations the importance of which has recently been discovered. I shall explain the basic framework showing the need for those phenomena, first, from a simple picture of the high-energy behaviour, then, giving a short derivation of the equation driving this evolution. In the second part, I shall exhibit an analogy with statistical physics and show how this allows to derive geometric scaling in QCD with saturation. I shall finally consider the effects of gluon-number fluctuations on this picture and draw the physical consequences, i.e. a new scaling law, arising from those results.
22 pages, 16 figures, invited lectures at the Cracow School of Theoretical Physics, Zakopane, June 2006
22 pages, 16 figures, invited lectures at the Cracow School of Theoretical Physics, Zakopane, June 2006