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LoopScalla

license: GPLv3

LoopScalla is a software framework that uses FORM, Mathematica and FeynCalc to calculate multiloop diagrams.

In its current stage it is merely a preview not ready for productive usage.

QGRAF conventions

  • incoming fields receive odd indices (-1, -3, -5, ...)
  • outging fields receive even indices (-2, -4, -6, ...)

Loopscalla conventions

  • p1, p2, ... denote incoming momenta

  • q1, q2, ... denote outgoing momenta

  • k1, k2, ... denote loop momenta

  • lsclMu1, lsclMu2, ... denote internal Lorentz indices

  • lsclNu1, lsclNu2, ... denote external Lorentz indices

  • lsclCFi1, lsclCFi2, ... denote internal fundamental color indices

  • lsclCFj1, lsclCFj2, ... denote external fundamental color indices

  • lsclCAi1, lsclCAi2, ... denote internal adjoint color indices

  • lsclCAj1, lsclCAj2, ... denote external adjoint color indices

  • lsclDi1, lsclDi2, ... denote internal Dirac indices

  • lsclDj1, lsclDj2, ... denote external Dirac indices

Available shell scripts

Evaluation stages

  • Stage 0 - Dirac and color algebra, expansions, kinematic simplifications. Projectors or tensor reduction. The output should be ready for the topology identification step

  • Stage 1 - Application of loop momenta shifts and topology mapping, rewriting of scalar propoducts in terms of inverse propagators. The output should be free any explicit loop momenta.

  • Stage 2 - Insertion of IBP reduction tables.

Command line parameters

Can add -d LSCLVERBOSITY=1 to the bash scripts to have a more verbose output

Creating new project

./ShellScripts/lsclAddNewProject.sh MyProject MyModel MyProcess1 MyProcess2 ...

Script naming

Most scripts will have following suffixes attached to their names:

  • All: meaning that all diagrams will be processed
  • FromTo: only the given range of diagrams will be processed
  • Force: force the recalculation of diagrams that have already been processed

Running jobs on a cluster where we reserve complete nodes

  • The requested memory should be the product of average memory requirement per single task times the number of simultaneous GNU parallel jobs. For example, for 4GB per task and 8 jobs we need at least 32 GB of RAM.
  • The number slices specifies the total number of jobs to be processed by a node. In general, the total number of single tasks divivded by the number of requested nodes should be a good number