8 research outputs found
Universality and tree structure of high energy QCD
Using non-trivial mathematical properties of a class of nonlinear evolution
equations, we obtain the universal terms in the asymptotic expansion in
rapidity of the saturation scale and of the unintegrated gluon density from the
Balitsky-Kovchegov equation. These terms are independent of the initial
conditions and of the details of the equation. The last subasymptotic terms are
new results and complete the list of all possible universal contributions.
Universality is interpreted in a general qualitative picture of high energy
scattering, in which a scattering process corresponds to a tree structure
probed by a given source.Comment: 4 pages, 3 figure
Traveling wave fronts and the transition to saturation
We propose a general method to study the solutions to nonlinear QCD evolution
equations, based on a deep analogy with the physics of traveling waves. In
particular, we show that the transition to the saturation regime of high energy
QCD is identical to the formation of the front of a traveling wave. Within this
physical picture, we provide the expressions for the saturation scale and the
gluon density profile as a function of the total rapidity and the transverse
momentum. The application to the Balitsky-Kovchegov equation for both fixed and
running coupling constants confirms the effectiveness of this method.Comment: 9 pages, 3 figures, references adde
Effective Regge QCD
A new framework for a high energy limit of quantum gauge field theories is
introduced. Its potency is illustrated on a new derivation of the reggeization
of the gluon.Comment: Latex, 9 pages + 2 figures as PS-file, extended version, to appear in
Phys. Rev. Let
Forward jet production in deep inelastic ep scattering and low-x parton dynamics at HERA
Differential inclusive jet cross sections in neutral current deep inelastic
ep scattering have been measured with the ZEUS detector. Three phase-space
regions have been selected in order to study parton dynamics where the effects
of BFKL evolution might be present. The measurements have been compared to the
predictions of leading-logarithm parton shower Monte Carlo models and
fixed-order perturbative QCD calculations. In the forward region, QCD
calculations at order alpha_s^1 underestimate the data up to an order of
magnitude at low x. An improved description of the data in this region is
obtained by including QCD corrections at order alpha_s^2, which account for the
lowest-order t-channel gluon-exchange diagrams, highlighting the importance of
such terms in parton dynamics at low x.Comment: 25 pages, 4 figure