NJET
Numerical evaluation of virtual corrections to multi-jet production in massless QCD.
The NJET package allows the computation of QCD scattering amplitudes including massless quarks at next-to-leading order (NLO) accuracy. As basic building blocs the library calculates primitive amplitudes involving gluons and massless quarks. The multiplicity of the primitive amplitudes is only restricted by numerical accuracy and runtime. Extended precision arithmetics can be used to improve the numerical accuracy. In addition, the package provides explicit results for all color summed squared matrix elements required for four jet and five jet production in hadronic collisions at NLO accuracy. The package has been applied recently to calculate the four jet production at NLO accuracy.
Written by: S.Badger, B.Biedermann, P.Uwer, V.Yundin
Published in: "Numerical evaluation of virtual corrections to multi-jet production in massless QCD", arXiv:1209.0100
The calculation of the four jet cross section is described in "NLO QCD corrections to multi-jet production at the LHC with a centre-of-mass energy of sqrt(s)=8 TeV", arXiv:1209.0098
NJET can be obtained here.
More information can also be found at https://bitbucket.org/njet/njet/