Location: Cyclotron Building (434), Seminar Room
Dr. Anna Stasto
High energy limit and parton saturation in QCD
Abstract:
The high-energy limit of QCD is an area of major theoretical interest. One of its predictions is the so called perturbative BFKL Pomeron which manifests itself as a rapid growth of the gluon density with increasing center-of-mass energy. Although the rise of this density is indeed observed in deep inelastic experiments at small values of Bjorken x, it is not compatible quantitatively with the prediction of the BFKL Pomeron. This lead to an intensive investigation of the possible corrections to the BFKL Pomeron such as higher order and high density corrections.
In this talk I will give an introduction to the high-energy limit of QCD and discuss the idea of parton saturation, an effect that is expected to occur when the gluon density is very high. I will describe the nonlinear evolution equation (Balitsky-Kovchegov equation) for the gluon density which takes into account high-density corrections and present its solution. The concept of the saturation scale and the geometrical scaling at small Bjorken x will be also introduced as well as the interesting link between parton saturation in QCD and statistical physics. Finally, I will discuss some phenomenological signatures of parton saturation and outline recent theoretical progress in developing a theory with so-called Pomeron loops, corrections which go beyond the Balitsky-Kovchegov equation.