madgraph.loop.loop_color_amp: Classes, methods and functions required to write QCD color
information for a loop diagram and build a color basis, and to
square a QCD color string for squared diagrams and interference
terms.
madgraph.loop.loop_helas_objects: Definitions of objects inheriting from the classes defined in
helas_objects.py and which have special attributes and function
devoted to the treatment of Loop processes