FeynGame 3.0

A major update of the program FeynGame is introduced. One of its main new functionalities is to visualize Feynman graphs generated by QGRAF. The QGRAF output can be either pasted into the FeynGame canvas for individual graphs, or the whole QGRAF output file can be processed. In addition, a number of new features and improvements have been implemented into FeynGame-3.0 in order to further facilitate the efficient drawing of Feynman diagrams in publication quality. FeynGame is freely available as jar or MacOS app file from https://web.physik.rwth-aachen.de/user/harlander/software/feyngame, and as source code from https://gitlab.com/feyngame/FeynGame.

💡 Research Summary

The paper presents FeynGame 3.0, a major upgrade of the Java‑based graphical tool for drawing and manipulating Feynman diagrams. The most noteworthy addition is the seamless integration of QGRAF, a fast diagram generator that traditionally outputs only human‑readable ASCII descriptions. FeynGame 3.0 can now ingest either a single QGRAF graph (by pasting the text into the canvas) or an entire QGRAF output file (via “File → Import qgraf”). The program parses the chosen QGRAF style file (e.g., form.sty, qgraf‑tapir.sty) to extract particle identifiers, vertex definitions, and line labels, then automatically creates a visual representation on the canvas.

To lay out the automatically generated graphs, FeynGame 3.0 employs a force‑directed spring‑layout algorithm originally described by Fruchterman and Reingold and later used in the TikZ‑Feynman LaTeX package. Vertices are modeled as equally charged masses, while propagators act as springs with a preferred length ℓ. The combination of repulsive Coulomb forces and attractive spring forces drives the system toward a minimal‑energy configuration, yielding aesthetically pleasing and topologically faithful placements without user intervention. Users can still fine‑tune the layout interactively by dragging vertices, rotating or stretching lines, and curving edges with the mouse wheel or trackpad.

A central design principle of FeynGame is its model‑based approach. Each particle in the underlying theory (Standard Model by default) is associated with a unique line style (wave, plain, spiral, color, thickness, arrow direction, etc.). When a QGRAF model file is used, the identifiers (e.g., “ph” for photon, “e” for electron, “E” for positron) must match those in the FeynGame model file. The authors describe three ways to achieve this synchronization: (1) manually edit the default FeynGame model file to adopt the QGRAF identifiers; (2) use the built‑in “Model Import qgraf model” function, which generates a compatible model file that can be further edited via the GUI’s EditFrame; (3) let FeynGame automatically create a new line style for any previously unknown particle and prompt the user to add it to the current model. This flexibility ensures that even custom beyond‑Standard‑Model theories can be visualized without extensive re‑coding.

Beyond the core QGRAF import, FeynGame 3.0 introduces a host of quality‑of‑life improvements. The GUI now features a double‑grid background, a file‑chooser preview pane, and enhanced LaTeX support for both line and vertex labels. Users can export diagrams to PDF, SVG, or other vector formats, and they can also generate the symbolic amplitude associated with a diagram in LaTeX form, facilitating rapid cross‑checks between algebraic and graphical representations.

Importantly, the tool is not limited to the graphical interface. A command‑line mode provides batch‑processing capabilities: commands such as “feyngame –import qgraf myfile.out –export pdf output/” allow integration into automated pipelines, for example in large‑scale perturbative calculations where thousands of diagrams are generated, inspected, and fed into symbolic manipulation programs.

The software is released under the GNU GPL v3, distributed as a platform‑independent JAR, a macOS application bundle, and as source code on GitLab. The authors emphasize the open‑source nature to encourage community contributions, such as adding new particle models, implementing alternative layout algorithms, or creating plugins for specific workflow integrations.

In conclusion, FeynGame 3.0 bridges the gap between fast diagram generation (QGRAF) and high‑quality visual output, offering an intuitive, model‑aware, and highly configurable environment for both educational purposes and professional research. By automating the translation from ASCII graph specifications to publication‑ready figures, and by providing both GUI and CLI interfaces, the tool significantly reduces the manual overhead traditionally associated with debugging and presenting large sets of Feynman diagrams. Future directions mentioned include expanding the library of built‑in models, adding cloud‑based collaborative editing, and exploring AI‑driven layout optimization to further streamline the diagram‑creation workflow.