The HEP Process Repository

This site attempts to provide a base of readily-available computer codes for one-loop calculations of scattering processes in high-energy physics in both the Standard Model and the MSSM.

The processes provided here have been generated with FeynArts and FormCalc and are downloadable as Fortran-77 source code. (Distributing executable code is rather pointless because parameters of the calculation cannot be modified then.) The results have been checked against published results as indicated by the references.

The calculation of the one-loop corrections has been performed in 't Hooft-Feynman gauge. Ultraviolet divergences are treated within dimensional regularization. For the renormalization the on-shell scheme [RoT73] is used, following the formulation worked out in [De93]. The IR divergences caused by the exchange of virtual photons are regularized by an infinitesimal photon mass and treated within the soft-photon approximation.

Please keep in mind that this is an experimental project. For example, the documentation is not as plentiful as we'd like it to be, but we're working on this. Note further that the programs offered here are not commercial. This site is hosted at the Institute for Theoretical Physics at the University of Karlsruhe.

The Fortran programs available here have been checked against results from the literature so that we reasonably believe they produce the right numbers. Needless to say, there is of course no guarantee on the correctness of the results. (But if you find any bugs, please let us know!)
You can use these programs for whatever you want. You don't have to pay us.
You may not pretend that you wrote these programs. If you use any of them in your program, you must acknowledge somewhere in your publication that you've used our code.

NEW Changes of 14 Dec 00:

updated graphics to FeynArts 3 format,

fixed problem with non-detection of CERNlib in configure,

added ee -> tt without QED corrections.

Process	Standard Model	MSSM	References
e⁺e^- -> \bar t t	eett_sm.tar.gz [39 kB] Diagrams: [born] [self] [vert] [box] [counter] the same w/o QED corrections and bremsstrahlung: eett_smnoqed.tar.gz [35 kB] Diagrams: [born] [self] [vert] [box] [counter]	eett_mssm.tar.gz [68 kB] Diagrams: [born] [self] [vert] [box] [counter]	[HoS99]
e⁺e^- -> W⁺W^-	eeWW_sm.tar.gz [47 kB] Diagrams: [born] [self] [vert] [box] [counter] in background-field method [DeDW95]: eeWW_smbgf.tar.gz [42 kB] Diagrams: [born] [self] [vert] [box] [counter]	eeWW_mssm.tar.gz [79 kB] Diagrams: [born] [self] [vert] [box] [counter]	[BeD94] [Ha00]
e⁺e^- -> H⁺H^-	N/A	eeHH_mssm.tar.gz [52 kB] Diagrams: [born] [self] [vert] [box] [counter]	[GuHK99]
W⁺W^- -> W⁺W^-	WWWW_sm.tar.gz [107 kB] Diagrams: [born] [self] [vert] [box] [counter] in background-field method [DeDW95]: WWWW_smbgf.tar.gz [74 kB] Diagrams: [born] [self] [vert] [box] [counter]	--	[DeH98]
ZZ -> ZZ	ZZZZ_sm.tar.gz [70 kB] Diagrams: [born] [self] [vert] [box] [counter] in background-field method [DeDW95]: ZZZZ_smbgf.tar.gz [58 kB] Diagrams: [born] [self] [vert] [box] [counter]	--	[DeDH97]

Note: the references given in this table are by no means a comprehensive survey of the literature for each process. They are merely the ones we have compared our results to.

Technical requirements: a Fortran-77 compiler and GNU make are needed to compile the code. For linking, LoopTools and the CERNlib must be installed.

Installation:

download and unpack the gzipped tar archive,
run "./configure" which will figure out the proper switches for your Fortran compiler,
run "gmake" to compile the code.

Running the compiled code:

the executable produced by gmake is by default called run,
invoke run as follows:
- to compute a differential cross-section:
  run <p₁> <p₂> <p₃> <p₄> <sqrts>
- to compute a total cross-section:
  run <p₁> <p₂> <p₃> <p₄> <sqrts_from> <sqrts_to>
p₁, p₂, p₃, p₄ specify the polarizations of the external particles and can take the values 0, +, -, t for longitudinal, right-circular, left-circular, transverse polarizations, or u for unpolarized particles.

Changing Input Parameters:

model parameters (masses, coupling constants, etc.) can be changed in model.h, sm_ini.F, and mssm_ini.F,
process parameters (e.g. the cutoff-energy for soft bremsstrahlung) can be changed in process.h,
parameters for a single "run" (e.g. regularization parameters, parameter regions to scan) can be changed in run.F.

More detailed information on the structure of the Fortran code can be found in the FormCalc documentation.

References

[De93]: A. Denner, Fortschr. Physik 41 (1993) 307.
[DeDH97]: A. Denner, S. Dittmaier, and T. Hahn, Phys. Rev. D56 (1997) 117 (hep-ph/9612390).
[DeDW95]: A. Denner, S. Dittmaier, and G. Weiglein, Nucl. Phys. B440 (1995) 95 (hep-ph/9410338).
[DeH98]: A. Denner and T. Hahn, Nucl. Phys. B525 (1998) 27 (hep-ph/9711302).
[BeD94]: W. Beenakker and A. Denner, Int. J. Mod. Phys. A9 (1994) 4837.
[Ha00]: T. Hahn (hep-ph/0007062).
[HoS99]: W. Hollik, C. Schappacher Nucl. Phys. B545 (1999) 98 (hep-ph/9807427).
[GuHK99]: J. Guasch, W. Hollik, and A. Kraft Nucl. Phys. B596 (2001) 66 (hep-ph/9911452).
Their Fortran code is available at http://www-itp.physik.uni-karlsruhe.de/~guasch/progs/eehh.html.
[RoT73]: D.A. Ross and J.C. Taylor, Nucl. Phys. B51 (1973) 125, E Nucl. Phys. B58 (1973) 643;
A. Sirlin, Phys. Rev. D22 (1980) 971;
K. I. Aoki et al., Suppl. Prog. Theor. Phys. 73 (1982) 1;
M. Böhm, W. Hollik, and H. Spiesberger, Fortschr. Physik 34 (1986) 687.

Thanks for looking in.

Please send bug reports, suggestions, fan mail, etc. to hahn@feynarts.de.

Last update: 2 Jul 01.
Repository maintainers: Thomas Hahn, Christian Schappacher.