AutoDipole – Automated generation of dipole subtraction terms –

We present an automated generation of the subtraction terms for next-to-leading order QCD calculations in the Catani–Seymour dipole formalism. For a given scattering process with n external particles our Mathematica package generates all dipole terms, allowing for both massless and massive dipoles. The numerical evaluation of the subtraction terms proceeds with MadGraph, which provides Fortran code for the necessary scattering amplitudes. Checks of the numerical stability are discussed.Program summaryProgram title: AutoDipoleCatalogue identifier: AEGO_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEGO_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 138 042No. of bytes in distributed program, including test data, etc.: 1 117 665Distribution format: tar.gzProgramming language: Mathematica and FortranComputer: Computers running Mathematica (version 7.0)Operating system: The package should work on every Linux system supported by Mathematica. Detailed tests have been performed on Scientific Linux as supported by DESY and CERN and on openSUSE and Debian.RAM: Depending on the complexity of the problem, recommended at least 128 MB RAMClassification: 11.5External routines: MadGraph (including HELAS library) available under http://madgraph.hep.uiuc.edu/ or http://madgraph.phys.ucl.ac.be/ or http://madgraph.roma2.infn.it/. A copy of the tar file, MG_ME_SA_V4.4.30, is included in the AutoDipole distribution package.Nature of problem: Computation of next-to-leading order QCD corrections to scattering cross sections, regularization of real emission contributions.Solution method: Catani–Seymour subtraction method for massless and massive partons [1,2]; Numerical evaluation of subtracted matrix elements interfaced to MadGraph [3–5] (stand-alone version) using helicity amplitudes and the HELAS library [6,7] (contained in MadGraph).Restrictions: Limitations of MadGraph are inherited.Running time: Dependent on the complexity of the problem with typical run times of the order of minutes.References:[1]S. Catani, M.H. Seymour, Nuclear Phys. B 485 (1997) 291, hep-ph/9605323.[2]S. Catani, et al., Nuclear Phys. B 627 (2002) 189, hep-ph/0201036.[3]T. Stelzer, W.F. Long, Comput. Phys. Comm. 81 (1994) 357, hep-ph/9401258.[4]F. Maltoni, T. Stelzer, JHEP 0302 (2003) 027, hep-ph/0208156.[5]J. Alwall, et al., JHEP 0709 (2007) 028, arXiv:0706.2334 [hep-ph].[6]K. Hagiwara, H. Murayama, I. Watanabe, Nuclear Phys. B 367 (1991) 257.[7]H. Murayama, I. Watanabe, K. Hagiwara, KEK-91-11.