DiagramVertex

Symbolica documentation for getting started, symbolic expressions, numerical evaluation, pattern matching, and APIs in Python and Rust.

`DiagramVertex`

class DiagramVertex

An interaction point in a Feynman diagram.

External states belong to edges; every public vertex references an interaction.

Examples

from symbolica import S, E
from symbolica.community import hepkit as hep
model = hep.Model.phi4()
process = model.process(["phi", "phi"], ["phi", "phi"])
result = process.generate_diagrams(loops=1)
diagram = result.diagrams[0]
vertex = diagram.vertices[0]
interaction = model.vertex_rule(vertex.interaction)
factor = vertex.numerator_expression()

Attributes

Name	Description
`id`	Return this vertex’s integer ID within the diagram.
`interaction`	Return the interaction name
`name`	Return the stable vertex label stored in the diagram.
`numerator`	Return the symbolic numerator annotation as source text

`id`

DiagramVertex.id: builtins.int

Return this vertex’s integer ID within the diagram.

Examples

Using the setup in the DiagramVertex class example:

vertices_by_id = {item.id: item for item in diagram.vertices}

`interaction`

DiagramVertex.interaction: builtins.str

Return the interaction name.

Raises :class:DiagramError for an incomplete imported diagram.

Examples

Using the setup in the DiagramVertex class example:

vertex = diagram.vertices[0]
rule = model.vertex_rule(vertex.interaction)

`name`

DiagramVertex.name: builtins.str

Return the stable vertex label stored in the diagram.

Examples

Using the setup in the DiagramVertex class example:

vertex_names = [item.name for item in diagram.vertices]

`numerator`

DiagramVertex.numerator: builtins.str

Return the symbolic numerator annotation as source text.

Raises :class:DiagramError when the diagram does not carry an instantiated Feynman-rule numerator for this vertex.

Examples

Using the setup in the DiagramVertex class example:

source_text = vertex.numerator
factor = vertex.numerator_expression()

Methods

Name	Description
`__repr__`	Return a concise, unambiguous description of the vertex.
`_repr_pretty_`	Write the vertex summary to an IPython pretty printer.
`numerator_expression`	Return the numerator annotation as a Spenso TensorExpression.

`repr`

DiagramVertex.__repr__() -> builtins.str

Return a concise, unambiguous description of the vertex.

Examples

Using the setup in the DiagramVertex class example:

vertex = diagram.vertices[0]
print(vertex)  # includes its external state or interaction rule

`_repr_pretty_`

DiagramVertex._repr_pretty_(pretty: typing.Any, cycle: builtins.bool) -> None

Write the vertex summary to an IPython pretty printer.

Examples

Using the setup in the DiagramVertex class example:

from IPython.lib.pretty import pretty
text = pretty(vertex)

Parameters

pretty (Any) The IPython pretty-printer object.
cycle (bool) Whether this object is part of a recursive formatting cycle.

`numerator_expression`

DiagramVertex.numerator_expression() -> TensorExpression

Return the numerator annotation as a Spenso TensorExpression.

Examples

Using the setup in the DiagramVertex class example:

vertex = diagram.vertices[0]
vertex_factor = vertex.numerator_expression()
weighted_vertex_factor = diagram.overall_factor_expression() * vertex_factor