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Manuscript Title: Algebraic reduction of one-loop Feynman diagrams to scalar integrals.
Authors: R.G. Stuart
Program title: LERG-I
Catalogue identifier: ABBX_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 48(1988)367
Programming language: Reduce.
Computer: IBM 4381.
Operating system: VM/SP.
Keywords: General purpose, Diagramatic expansions, Gauge theories, Renormalizable theories, Scalar integrals, One-loop integrals, Feynman diagrams, Dimensional Regularization, Reduce.
Classification: 4.4, 5.

Nature of problem:
Expressions obtained in the calculation of one-loop radiative corrections to processes in high energy physics are generally simplified by expressing them in terms of scalar integrals. LERG-I makes the reduction from form factors corresponding to the various possible Lorentz tensors occuring in the problem.

Solution method:
The program makes use of identities that, in the context of dimensional regularization, relate the various form factors to one and other in a hierarchical fashion. The end result is that all form factors are finally defined in terms of scalar integrals.

Processes with up to four external particles can be treated. Machine storage is generally the only limitation.

Running time:
Depends heavily on the complexity of the problem. The test runs took 26 and 29 seconds total CPU time respectively. To initialize the C4 form factors with all arguments different and non-zero takes 259 CPU seconds.