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Manuscript Title: ALOHA: Automatic Libraries Of Helicity Amplitudes for Feynman diagram computations
Authors: Priscila de Aquino, William Link, Fabio Maltoni, Olivier Mattelaer, Tim Stelzer
Program title: ALOHA
Catalogue identifier: AEMS_v1_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 183(2012)2254
Programming language: Python2.6.
Computer: 32/64 bit.
Operating system: Linux/Mac/Windows.
RAM: 512 Mbytes
Keywords: Helicity Routine, Feynman Rules, Feynman diagram.
Classification: 4.4, 11.6.

Nature of problem:
An effcient numerical evaluation of a squared matrix element can be done with the help of the helicity routines implemented in the HELAS library [1]. This static library contains a limited number of helicity functions and is therefore not always able to provide the needed routine in the presence of an arbitrary interaction. This program provides a way to automatically create the corresponding routines for any given model.

Solution method:
ALOHA takes the Feynman rules associated to the vertex obtained from the model information (in the UFO format [2]), and multiplies it by the different wavefunctions or propagators. As a result the analytical expression of the helicity routines is obtained. Subsequently, this expression is automatically written in the requested language (Python, Fortran or C++)

Restrictions:
The allowed fields are currently spin 0, 1/2, 1 and 2, and the propagators of these particles are canonical.

Running time:
A few seconds for the SM and the MSSM, and up to a few minutes for models with spin 2 particles.

References:
[1] Murayama, H. and Watanabe, I. and Hagiwara, K., HELAS: HELicity Amplitude Subroutines for Feynman diagram evaluations, KEK-91-11, (1992) http://www-lib.kek.jp/cgi-bin/img\_index?199124011
[2] C. Degrande, C. Duhr, B. Fuks, D. Grellscheid, O. Mattelaer, et al., UFO - The Universal FeynRules Output, Comput. Phys. Commun. 183 (2012) 1201-1214. arXiv:1108.2040, doi:10.1016/j.cpc.2012.01.022.