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Manuscript Title: OneLOop: for the evaluation of one-loop scalar functions
Authors: A. van Hameren
Program title: OneLOop
Catalogue identifier: AEJO_v1_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 182(2011)2427
Programming language: Fortran.
Computer: Workstations.
Operating system: Linux, Unix.
RAM: Negligible
Keywords: NLO computations, one-loop scalar functions.
PACS: 12.38.Bx.
Classification: 4.4, 11.1.

Nature of problem:
In order to reach next-to-leading order precision in the calculation of cross sections of hard scattering processes, one-loop amplitudes have to be evaluated. This is done by expressing them as linear combination of one-loop scalar functions. In a concrete calculation, these functions eventually have to be evaluated. If the scattering process involves unstable particles, consistency requires the evaluation of these functions with complex internal masses.

Solution method:
Expressions for the one-loop scalar functions in terms of single-variable analytic functions existing in literature have been implemented.

Restrictions:
The applicability is restricted to the kinematics occuring in collider-physics.

Running time:
The evaluation of the most general 4-point function with 4 complex masses takes about 180μs, and the evaluation of the 4-point function with 4 real masses takes about 18μs on a 2.80GHz Intel Xeon processor.