HELAC-DIPOLES  includes the massless dipole formalism of  Catani and Seymour,  as well as its massive version as developed by Catani, Dittmaier, Seymour and Trocsanyi, for arbitrary helicity eigenstates of the external partons. Phase space integration of subtracted real radiation and integrated dipoles in both massless and massive cases is implemented and performed with the help of Monte Carlo generators PHEGAS and KALEUA phase space restriction on the contribution of the dipoles is also added. 

The HELAC-DIPOLES package has been extended with the implementation of a new subtraction formalism, first introduced by Nagy and Soper in the formulation of an improved parton shower.  A semi-numerical  approach for the evaluation of the integrated subtraction  terms for both massless and massive partons has been implemented, which provides the missing ingredient for a complete implementation. The new scheme can now be used for processes with  arbitrary parton masses and multiplicities.  Random polarization and color sampling of the external partons is also included.

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Malgorzata Worek 
Michal Czakon 
Costas G. Papadopoulos
Giuseppe Bevilacqua
Michael Kubocz

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  lahey 95
  Intel Fortran

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Software Download

    DIPOLES 2.2.1 (8 October 2014): helac-dipoles-2.2.1.tgz 
Preconfigured version (HELAC-PHEGAS+DIPOLES)
                     README with installation and usage instructions included
                     KALEU phase-space generator incorporated into the HELAC-DIPOLES package

DIPOLES 2.1.1 (11 February 2014): helac-dipoles-2.1.1.tgz

DIPOLES 2.1.0 (16 December 2013): helac-dipoles-2.1.0.tgz 

DIPOLES 2.0.0 (26 August 2013): helac-dipoles-2.0.0.tgz

DIPOLES  1.1.1
(16 October 2011): dipoles.1.1.1.tgz  

DIPOLES  1.1.0
(27 July 2009):
the README file contains installation and usage instructions

DIPOLES:  preconfigured.tgz
Preconfigured version to reproduce the results from the paper

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The following paper should be cited while using HELAC-DIPOLES package

Polarizing the Dipoles
M. Czakon, C. G. Papadopoulos and M. Worek
JHEP 0908 (2009) 085

Complete Nagy-Soper subtraction for next-to-leading order calculations in QCD
G. Bevilacqua, M. Czakon, M. Kubocz and M. Worek
JHEP 1310 (2013) 204

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News & Developments 

Changes in HELAC-DIPOLES Version 2.2.1

   A few bugs have been fixed (e.g. for the problem found  in the integrated dipoles part of Nagy-Soper implementation in case of ud -> tb

Changes in HELAC-DIPOLES Version 2.1.1

     A few minor bugs have been cured. README with installation and usage instructions included

Changes in HELAC-DIPOLES Version 2.1.0

     KALEU phase space generator incorporated into the HELAC-DIPOLES package (to compile "make kaleu")   
     A bug for the .sumtype.eq.0 option fixed (fast sum option)
README with installation and usage instructions included in the dipole directory

Changes in HELAC-DIPOLES Version 2.0.0

     New Nagy-Soper subtraction scheme for both massless and massive partons
  Dynamical factorization and renormalization scales
  Three different jet algorithms (kT, anti-kT, Cambridge/Aachen)
  Random color sampling
  Random polarization sampling for Nagy-Soper scheme
  Interface to the LHAPDF library
  Interface to the KALEU phase space generator, which associates separate channel for each term in the real-subtracted integral
  Deterministic Gaussian integration in the KP-operator part of the integrated dipoles replaced with Monte Carlo integration
  Summation over PDFs for the subtracted real emission part and I-operator

Changes in HELAC-DIPOLES Version 1.1.1

     Makefile modification (to be run with HELAC-PHEGAS Curent Version 1.2.2)

Changes in HELAC-DIPOLES Version 1.1.0

     Integrated dipoles implemented for massless and massive cases
  Phase space restriction dependence included in the massless and massive cases
  A bug in the jet function fixed
  Phase space integrator corrected

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Contact us

If you have a question, comment, suggestion or bug report, please e-mail us at:



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Last modified by Malgorzata Worek
Wed, Oct 8th, 2014