Scattering AMplitudes from Unitarity-based

Reduction Algorithm at Integrand level

Authors: P. Mastrolia, G. Ossola, T. Reiter and F. Tramontano

for details see arXiv:1006.0710


SAMURAI is a tool for the automated numerical evaluation of one-loop virtual corrections to any scattering amplitudes within the dimensional regularization scheme. It is based on the decomposition of the integrand according to the OPP-approach, extended to accommodate an implementation of the generalised D-dimensional unitarity-cuts technique, and uses a polynomial interpolation exploiting the Discrete Fourier Transform. SAMURAI can process integrands with any number of external legs, written either as numerator of Feynman diagrams or as product of tree level amplitudes and it can be compiled in double or quadruple precision. For more details view the documentation (PDF).


The source is available as a tar'ed and gzip'ed package, which extracts the files into a directory called samurai_v1.0. The compilation can be done by running the Install command. This will also compile the two packages for the evaluation of the scalar integrals: QCDLOOP and AVH-OLO. The code has been developed and tested under Ubuntu and Mac OSX, please report any compilation problems under other operating systems to the authors.


The distribution contains a dedicated directory with examples of calculations performed with SAMURAI. The examples could be used as a guide to understand the framework, as templates to generate the codes for other virtual processes or to design an interface with other tools.

1. Examples with integrands given as numerators of Feynman diagrams

2. Examples with integrands given as product of tree level amplitudes

Related codes

A package for the evaluation of the scalar integrals needs to be linked to SAMURAI to get full numerical results. SAMURAI has been linked to the following two libraries:



Last update: June 2, 2010