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Manuscript Title: FIESTA 3: cluster-parallelizable multiloop numerical calculations in physical regions
Authors: A.V. Smirnov
Program title: FIESTA 3
Catalogue identifier: AECP_v3_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 185(2014)2090
Programming language: Wolfram Mathematica 7.0 or higher, C++.
Computer: From a desktop PC to a supercomputer.
Operating system: Unix, Linux, Mac OS X.
Has the code been vectorised or parallelized?: Yes. Number of processors used: from 1 processor up to loading a supercomputer (tests were performed up to 1024 cores)
RAM: Depends on the complexity of the problem
Keywords: Feynman diagrams, Multiloop Feynman integrals, Dimensional regularization, Computer algebra.
Classification: 4.4, 4.12, 5, 6.5.

External routines: Wolfram Mathematica [1], KyotoCabinet [2], Cuba [3], QHull [4]

Does the new version supersede the previous version?: Yes. Some obsolete options were removed as being superseded by better approaches.

Nature of problem:
The sector decomposition approach to evaluating Feynman integrals falls apart into the sector decomposition itself, where one has to minimize the number of sectors; the pole resolution and epsilon expansion; and the numerical integration of the resulting expression. Moreover, in cases where the integrand is complex, one has to perform a contour deformation.

Solution method:
The program has a number of sector decomposition strategies. One of the most important features is the ability to perform a contour deformation, as well as the so-called pre-resolution in the case of integrals at the threshold. Everything except the integration is performed in Wolfram Mathematica [1] (required version is 7.0 or higher). This part of the calculation is parallelizable with the use of shared memory. The database is stored on hard disk with the use of the KyotoCabinet [2] database engine. The integration part of the algorithm, which can be performed on a cluster, is written in c++ and does not need Wolfram Mathematica. For integration we use the Cuba library package [3].

Reasons for new version:
Application of FIESTA to physical values (complex integration) as well as the cluster-parallelization.

Summary of revisions:
FIESTA 3 is an absolutely new version with multiple new features such as
  • integration in physical regions
  • new asymptotic expansion methods
  • MPI-parallelization
  • multiple speed and memory improvements
  • total reconstruction: the integrator is completely separated and can be used by other programs

The complexity of the problem is mostly restricted by the CPU time required to perform the integration and obtain a proper precision.

Running time:
Depends on the complexity of the problem.

[1] http://www.wolfram.com/mathematica/, commercial algebraic software;
[2] http://fallabs.com/kyotocabinet/, open source;
[3] http://www.feynarts.de/cuba/, open source;
[4] http://www.qhull.org, open source.