HELAS: HELicity amplitude subroutines for Feynman diagram evaluations. HELAS is a set of the FORTRAN 77 subroutines which enable to compute the helicity amplitude of an arbitrary tree level Feynman diagram with a simple sequence of CALL SUBROUTINE statements. It is easy to write down a FORTRAN program to calculate the helicity amplitude of a given process by calling the HELAS subroutines. The example of evaluating the helicity amplitude of the process W+W-→t anti-t is shown. The compactness of the helicity amplitude programs is the main advantage of using the HELAS. Another advantage is that it is very easy to allow external heavy particles to decay into light quarks and leptons without losing the spin correlation. The procedure of calculating the cross section of an arbitrary process with the help of the HELAS and noteworthy characteristics of the HELAS system are shown. How to use the HELAS package is explained about the above example. The HELAS subroutines are grouped in wave functions, nine vertices and tools and standard model coupling constants. HELAS CHECK messages makes the job to find mistake easy.

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  1. Capatti, Zeno; Hirschi, Valentin; Kermanschah, Dario; Pelloni, Andrea; Ruijl, Ben: Numerical loop-tree duality: contour deformation and subtraction (2020)
  2. Jäger, Barbara; von Manteuffel, Andreas; Thier, Stephan: Slepton pair production in association with a jet: NLO-QCD corrections and parton-shower effects (2015)
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  6. Hagiwara, K.; Li, T.; Mawatari, K.; Nakamura, J.: TauDecay: a library to simulate polarized tau decays via FeynRules and MadGraph5 (2012) arXiv
  7. Alwall, Johan; Herquet, Michel; Maltoni, Fabio; Mattelaer, Olivier; Stelzer, Tim: MadGraph 5: going beyond (2011)
  8. Campanario, Francisco: Towards (pp \toVVjj) at NLO QCD: bosonic contributions to triple vector boson production plus jet (2011)
  9. De Aquino, Priscila; Hagiwara, Kaoru; Li, Qiang; Maltoni, Fabio: Simulating graviton production at hadron colliders (2011)
  10. Arnold, Ken; Figy, Terrance; Jäger, Barbara; Zeppenfeld, Dieter: Next-to-leading order QCD corrections to Higgs boson production in association with a photon via weak-boson fusion at the LHC (2010)
  11. Sumino, Yukinari; Yokoya, Hiroshi: Bound-state effects on kinematical distributions of top quarks at hadron colliders (2010)