Diffractive Interactions

The general framework of diffractive deep inelastic scattering is introduced and reports given in the session on diffractive interactions at the International Workshop on Deep-Inelastic Scattering and Related Phenomena, Rome, April 1996, are presented.Comment: LaTeX with procl.sty, 20 pages. To appear in the Proceedings of the International Workshop on Deep Inelastic Scattering and Related Phenomena, Roma, Italy, April 199

Feno e silagem como volumoso para confinamento de bovinos de corte.

bitstream/item/67190/1/CT-49-2001.pd

Dijet Production at Hadron--Hadron Colliders in the BFKL Approach

The production in high-energy hadron collisions of a pair of jets with large rapidity separation is studied in an improved BFKL formalism. By recasting the analytic solution of the BFKL equation as an explicit order-by-order sum over emitted gluons, the effects of phase space constraints and the running coupling are studied. Particular attention is paid to the azimuthal angle decorrelation of the jet pair. The inclusion of sub-leading effects significantly improves the agreement between the theoretical predictions and recent preliminary measurements from the Dzero collaboration.Comment: 19 pages LaTeX; one figure corrected; conclusions unchange

Infrared singularities of QCD scattering amplitudes in the Regge limit to all orders

Scattering amplitudes of partons in QCD contain infrared divergences which can be resummed to all orders in terms of an anomalous dimension. Independently, in the limit of high-energy forward scattering, large logarithms of the energy can be resummed using Balitsky-Fadin-Kuraev-Lipatov theory. We use the latter to analyze the infrared-singular part of amplitudes to all orders in perturbation theory and to next-to-leading-logarithm accuracy in the high-energy limit, resumming the two-Reggeon contribution. Remarkably, we find a closed form for the infrared-singular part, predicting the Regge limit of the soft anomalous dimension to any loop order.Comment: 35 pages, 8 figure

Hopf algebras, coproducts and symbols: an application to Higgs boson amplitudes

We show how the Hopf algebra structure of multiple polylogarithms can be used to simplify complicated expressions for multi-loop amplitudes in perturbative quantum field theory and we argue that, unlike the recently popularized symbol-based approach, the coproduct incorporates information about the zeta values. We illustrate our approach by rewriting the two-loop helicity amplitudes for a Higgs boson plus three gluons in a simplified and compact form involving only classical polylogarithms.Comment: 46 page

Computation of Mini-Jet Inclusive Cross Sections

We apply the theory of parton-parton total cross sections at large ``s", due to Lipatov and collaborators, to compute the inclusive cross section for jets which accompany a large ``s" parton scattering process.Comment: 13 page

Virtual Next-to-Leading Corrections to the Lipatov Vertex

We compute the virtual next-to-leading corrections to the Lipatov vertex in the helicity-amplitude formalism. These agree with previous results by Fadin and collaborators, in the conventional dimensional-regularization scheme. We discuss the choice of reggeization scale in order to minimize its impact on the next-to-leading-logarithmic corrections to the BFKL equation.Comment: Latex, 20 pages, no figures; One minor typo fixed. References added. To be published in Phys. Rev.

An Analytic Result for the Two-Loop Hexagon Wilson Loop in N = 4 SYM

In the planar N=4 supersymmetric Yang-Mills theory, the conformal symmetry constrains multi-loop n-edged Wilson loops to be basically given in terms of the one-loop n-edged Wilson loop, augmented, for n greater than 6, by a function of conformally invariant cross ratios. We identify a class of kinematics for which the Wilson loop exhibits exact Regge factorisation and which leave invariant the analytic form of the multi-loop n-edged Wilson loop. In those kinematics, the analytic result for the Wilson loop is the same as in general kinematics, although the computation is remarkably simplified with respect to general kinematics. Using the simplest of those kinematics, we have performed the first analytic computation of the two-loop six-edged Wilson loop in general kinematics.Comment: 17 pages. Extended discussion on how the QMRK limit is taken. Version accepted by JHEP. A text file containing the Mathematica code with the analytic expression for the 6-point remainder function is include