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Manuscript Title: Golem95: a numerical program to calculate one-loop tensor integrals with up to six external legs
Authors: T. Binoth, J.-Ph. Guillet, G. Heinrich, E. Pilon, T. Reiter
Program title: golem95_v1.0
Catalogue identifier: AEEO_v1_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 180(2009)2317
Programming language: Fortran95.
Computer: Any computer with a Fortran95 compiler.
Operating system: Linux, Unix.
RAM: RAM used per form factor is insignificant, even for a rank six six-point form factor.
Keywords: NLO Computations, One-Loop Diagrams, Tensor Reduction.
PACS: 12.38.Bx.
Classification: 4.4, 11.1.

External routines: Perl programming language (http://www.perl.com/)

Nature of problem:
Evaluation of one-loop multi-leg tensor integrals occurring in the calculation of next-to-leading order corrections to scattering amplitudes in elementary particle physics.

Solution method:
Tensor integrals are represented in terms of form factors and a set of basic building blocks ("basis integrals"). The reduction to the basis integrals is performed numerically, thus avoiding the generation of large algebraic expressions.

Restrictions:
The current version contains basis integrals for massless internal particles only. Basis integrals for massive internal particles will be included in a future version.

Running time:
Depends on the nature of the problem. A rank 6 six-point form factor at a randomly chosen kinematic point takes 0.13 seconds on an Intel Core 2 Q9450 2.66GHz processor, without any optimisation. With compiler optimisation flag -O3 the same point takes 0.09 seconds.
Timings for lower point form factors are:
All form factors for five-point functions from rank 0 to rank 4: 0.04 s
All form factors for rank 5 five-point functions: 0.05 s
All form factors for four-point functions from rank 0 to rank 4: 0.01 s.