Qgraf–r computes particle number conservation rules (both additive and multiplicative) for many types of QFT models. It is then able to identify (un)physical processes that break those rules, thereby ruling out the existence of matching Feynman diagrams for any order of perturbation theory.
Additionally, it ‘solves’ inclusive processes with a fixed number of external fields, some of which ‘unknowns’ — that is, it can find the matching non-inclusive scattering processes that satisfy the number conservation rules it has computed itself. Specially when dealing with ‘complex’ models, this feature can be employed to search for processes that either produce certain kinds of particles or contribute to the background of some other scattering process.
The information produced by the program can also be used to partly cross-check the input model-file. For instance, if some of the rules of the (intended) model are known in advance, and if they are not compatible with those computed by the program, then the model-file is very likely to contain an incorrect description of that model.
Qgraf–r should be seen as a research tool, just like Qgraf.
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Latest version: qgraf-r-1.0 (2019)
Please report any error you may happen to find. -
Programming language: Fortran 77
No binaries either (see also the corresponding entry for Qgraf).
Most of the theory behind Qgraf–r is described in these papers:
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From Feynman rules to conserved quantum numbers, I
Comput. Phys. Commun. 214 (2017) 83–90
https://doi.org/10.1016/j.cpc.2017.01.025
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From Feynman rules to conserved quantum numbers, II
Comput. Phys. Commun. 215 (2017) 13–19
https://doi.org/10.1016/j.cpc.2017.01.027
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From Feynman rules to conserved quantum numbers, III
Comput. Phys. Commun. 260 (2021) 107740
https://doi.org/10.1016/j.cpc.2020.107740