Elsevier Science Home
Computer Physics Communications Program Library
Full text online from Science Direct
Programs in Physics & Physical Chemistry
CPC Home

[Licence| Download | New Version Template] aeoc_v1_0.tar.gz(2942 Kbytes)
Manuscript Title: HELAC-NLO
Authors: G. Bevilacqua, M. Czakon, M.V. Garzelli, A. van Hameren, A. Kardos, C.G. Papadopoulos, R. Pittau, M. Worek
Program title: HELAC-1LOOP
Catalogue identifier: AEOC_v1_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 184(2013)986
Programming language: Fortran (gfortran(http://gcc.gnu.org/fortran/), lahey95 (http://www.lahey.com), ifort3(http://software.intel.com)).
Computer: Any.
Operating system: Linux, Unix, Mac OS.
Keywords: QCD, NLO corrections, Scattering Amplitudes.
Classification: 11.1.

Nature of problem:
The evaluation of virtual one-loop amplitudes for multi-particle scattering is a longstanding problem [1]. In the last years the OPP reduction technique [2] opened the road for a fully numerical approach based on the evaluation of the one-loop amplitude for well-defined values of the loop momentum.

Solution method:
By using HELAC [3-5] and CutTools [6], HELAC-1LOOP is capable of evaluating QCD virtual corrections [7]. The one-loop n-particle amplitudes are constructed as part of the n + 2 tree-order ones, by using the basic recursive algorithm used in HELAC. A Les Houches Event (LHE) file is being produced combining the complete information from tree- and virtual one-loop contributions. In conjunction with real corrections, obtained with the use of HELAC-DIPOLES [8], the full NLO corrections can be computed. The program has been successfully used in many applications.

Running time:
Depending on the number of particles and generated events from seconds to days.

[1] R.K. Ellis, Z. Kunszt, K. Melnikov and G. Zanderighi, arXiv:1105.4319 [hepph].
[2] G. Ossola, C. G. Papadopoulos and R. Pittau, Nucl. Phys. B 763 (2007) 147 [arXiv:hep-ph/0609007].
[3] A. Kanaki and C. G. Papadopoulos, Comput. Phys. Commun. 132 (2000) 306 [arXiv:hep-ph/0002082].
[4] C. G. Papadopoulos, Comput. Phys. Commun. 137 (2001) 247 [arXiv:hepph/ 0007335].
[5] A. Cafarella, C. G. Papadopoulos and M. Worek, Comput. Phys. Commun. 180 (2009) 1941 [arXiv:0710.2427 [hep-ph]].
[6] G. Ossola, C. G. Papadopoulos and R. Pittau, JHEP 0803 (2008) 042 [arXiv:0711.3596 [hep-ph]].
[7] A. van Hameren, C. G. Papadopoulos and R. Pittau, JHEP 0909, 106 (2009) [arXiv:0903.4665 [hep-ph]].
[8] M. Czakon, C. G. Papadopoulos and M. Worek, JHEP 0908, 085 (2009) [arXiv:0905.0883 [hep-ph]].