FeynML

FeynML is a project to develop an XML dialect for describing Feynman diagrams as used in quantum field theory calculations. The primary aim is to unambiguously describe the structure of a diagram in XML, giving a de facto representation for diagram structure which can be easily translated into another representation.

Why XML?

Okay, XML is a bit of a buzzword. Not everything is best-represented as XML. However, it does have several benefits: it is simple to read and write, both for humans and computers; there are a variety of technologies available for parsing, styling and transforming XML (see e.g. SAX, DOM, CSS, XSLT) and its heirarchical structure maps fairly well into describing graphs. The variety of technologies aspect is probably the most important.

Elements

A Feynman diagram is constructed of

• Leg
• Vertex
• Propagator
• Label

Attributes

Above buildings blocks come with different attributes, which are described in the following sections

Attributes	pyx	feynmp	tikz	dot	feynman	mpl	ascii	unicode
X	✔	✖	✔	✔	✔	✔	✔	✔
Y	✔	✖	✔	✔	✔	✔	✔	✔
Bend	✔	✖	✖	✖	✖	✖	✖	✖
Label	✔	✔	✔	✔	✔	✖	✔	✔
PDGID	✔	✔	✔	✔	✔	✔	✔	✔
Sense	✔	✔	✔	✔	✔	✔	✔	✔
Target	✔	✔	✔	✔	✔	✔	✔	✔
Source	✔	✔	✔	✔	✔	✔	✔	✔
Style	✔	✖	✔	✖	✖	✖	✖	✖
ID	✔	✔	✔	✔	✔	✔	✔	✔
Type	✔	✔	✔	✔	✔	✔	✔	✔
Text	✖	✖	✖	✖	✖	✖	✖	✖
Momentum	✖	✖	✔	✖	✖	✖	✖	✖
Tension	✖	✖	✖	✖	✖	✖	✖	✖

Examples

• Write FeynmanDiagram
• Write FeynML
• Read FeynML