Color-flow decomposition of QCD amplitudes
نویسندگان
چکیده
We introduce a new color decomposition for multi-parton amplitudes in QCD, free of fundamental-representation matrices and structure constants. This decomposition has a physical interpretation in terms of the flow of color, which makes it ideal for merging with shower Monte-Carlo programs. The color-flow decomposition allows for very efficient evaluation of amplitudes with many quarks and gluons, many times faster than the standard color decomposition based on fundamental-representation matrices. This will increase the speed of event generators for multi-jet processes, which are the principal backgrounds to signals of new physics at colliders.
منابع مشابه
Constructing Scattering Amplitudes Lecture 3: Twistors and N = 4 Supersymmetric Yang-Mills
The main theme of these lectures is the construction of scattering amplitudes from their singularities. We have seen how complex poles are used in the BCFW construction, and later on we will discover the use of branch cuts and related singularities for loop amplitudes. In this lecture, we take a step aside and consider the construction of amplitudes from their symmetries, incarnating the simpli...
متن کامل/ 97 08 34 2 v 1 1 3 A ug 1 99 7 hep - ph / 9708342 Group independent color decomposition of next - to - leading order matrix elements for e + e − → four partons
We present the next-to-leading order partonic cross sections involving an electroweak vector boson and four massless partons (quarks, gluons or long living gluinos) in a general gauge theory with a simple Lie Group. The vector boson couples to a massless lepton pair and a quark-antiquark pair. The cross sections are given in terms of group independent kinematical functions multiplying the eigen...
متن کاملStrings and Supersymmetry as Tools for Perturbative Qcd*
. We review techniques simplifying the analytic calculation of one-loop QCD amplitudes with many external legs, for use in next-to-leading-order corrections to multi-jet processes. We explain how a supersymmetry-inspired organization works well in conjunction with other tools, namely the color and helicity decompositions of amplitudes, and the constraints imposed by perturbative unitarity and c...
متن کاملTwo-Loop Helicity Amplitudes for Quark-Gluon Scattering in QCD and Gluino-Gluon Scattering in Supersymmetric Yang-Mills Theory
We present the two-loop QCD helicity amplitudes for quark-gluon scattering, and for quark-antiquark annihilation into two gluons. These amplitudes are relevant for next-to-next-to-leading order corrections to (polarized) jet production at hadron colliders. We give the results in the ‘t Hooft-Veltman and four-dimensional helicity (FDH) variants of dimensional regularization. The transition rules...
متن کاملMulti-gluon one-loop amplitudes numerically
A c++ implementation of the Ds-dimensional unitarity cut algorithm for the numerical evaluation of the virtual contribution to NLO QCD amplitudes is presented. The current version includes an arbitrary number of external gluons with gluonic propagators in the loop. The building blocks are tree level color-ordered amplitudes with gluons and with gluons and two scalars in five dimensions. Numeric...
متن کامل