Elsevier Science Home
Computer Physics Communications Program Library
Full text online from Science Direct
Programs in Physics & Physical Chemistry
CPC Home

[Licence| Download | New Version Template] aeeo_v1_0.tar.gz(235 Kbytes)
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.

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.