It is part of the philosophy of FeynGame to use a pre-defined
model (say, QED, the Standard Model, the MSSM, or a subset of the
associated particles) where each particle corresponds to a line with a
certain appearance. This makes it particularly efficient to draw a
particular diagram, because the different line styles for the individual
particles have been defined beforehand, using the model
file. A model file for describing the electro-weak interaction of the first two lepton generations would read
[ e, E, fermion, color=Red, label=e ]
[ nue, Nue, fermion, color=dc27e7, label=νe ]
[ mu, Mu, fermion, color=Green, label=μ]
[ numu, Numu, fermion, color=27e7b3,label=νμ ]
[ W, W, photon, color=dc27e7, label=W]
[ Z, Z, photon, color=Blue, label=Z]
[ ph, ph, photon, color=Green, label=γ ]
Each pair of square brackets
defines a particle. The first two entries assign an internal name for
the particle. If those are different from each other, it is assumed
that the particle is charged and an arrow is added to the line if not stated
otherwise. The third entry defines the basic line style. These three
entries are required when defining a line in the model file. The
label parameter is optional.
Starting FeynGame by giving it the name of the model file as argument (including its path) will load the specific model instead of the default one. It is possible to open additional model files by either pressing the ✚ right next to the tabs representing the currently opened model files or via File > Load model file. This lets one select a new model file to open. Upon confirmation, the new model file is added to the list of model files and can be activated by pressing the corresponding tab. One can press the ✖ on a tab to close the corrsponding model file and remove it form the list of model files.
A convenient option to modify the model file is to modify the appearance of an existing line within FeynGame (for example by using EditFrame), and then selecting the "+" tile in the main window.
To create a completely new model file, one can do so manually by creating a ".model" file and editing it in a text editor. Another way is to draw a diagram onto the canvas and then pressing File > Convert canvas to model. This will create a new model that contains all the objects that are drawn on the canvas. It also derives the Feynman rules from the vertices that are present on the canvas. It should be noted that lines and vertices are considered to be of the same type even if they have different descriptions.
One can also create a new model by merging several of the opened models by pressing File > Merge models . This opens another window where one can select the models that should be merged. Upon confirmation the new merged model will appear as one of the model tabs. The models that were merged remain unchanged