CffGenerator

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

`CffGenerator`

class CffGenerator

Generate Cross-Free Family energy denominators for Feynman diagrams.

The generator can constrain edge orientations or contractions before enumerating the acyclic energy flows of a loop diagram.

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]
generator = hep.CffGenerator(max_orientations=1000)
result = generator.generate(diagram)
expression = result.to_expression()

Parameters

max_orientations (int, optional) Maximum number of candidate edge orientations to inspect.

Methods

Name	Description
`__new__`	Create a configurable Cross-Free Family generator.
`contract_edge`	Contract an edge before generating denominator surfaces.
`fix_orientation`	Fix an edge to its stored or reversed direction.
`generate`	Generate a Cross-Free Family representation for a diagram.
`mark_initial_state_edge`	Mark an edge as belonging to the initial state.

`new`

CffGenerator.__new__(max_orientations: typing.Optional[builtins.int] = None) -> CffGenerator

Create a configurable Cross-Free Family generator.

Examples

Using the setup in the CffGenerator class example:

generator = hep.CffGenerator(max_orientations=1000)

Parameters

max_orientations (int, optional) Maximum number of candidate orientations to inspect.

`contract_edge`

CffGenerator.contract_edge(edge: builtins.int) -> None

Contract an edge before generating denominator surfaces.

Examples

Using the setup in the CffGenerator class example:

generator = hep.CffGenerator()
generator.contract_edge(diagram.internal_edges[0].id)
result = generator.generate(diagram)

Parameters

edge (int) Diagram edge ID to contract.

`fix_orientation`

CffGenerator.fix_orientation(edge: builtins.int, reversed: builtins.bool) -> None

Fix an edge to its stored or reversed direction.

Examples

Using the setup in the CffGenerator class example:

generator = hep.CffGenerator()
generator.fix_orientation(diagram.internal_edges[0].id, reversed=True)
result = generator.generate(diagram)

Parameters

edge (int) Diagram edge ID.
reversed (bool) Select the reversed direction when true.

`generate`

CffGenerator.generate(diagram: FeynmanDiagram) -> CffResult

Generate a Cross-Free Family representation for a diagram.

Examples

Using the setup in the CffGenerator class example:

generator = hep.CffGenerator()
result = generator.generate(diagram)
expression = result.to_expression()

Parameters

diagram (FeynmanDiagram) Diagram or subgraph whose energy-flow orientations are enumerated.

`mark_initial_state_edge`

CffGenerator.mark_initial_state_edge(edge: builtins.int) -> None

Mark an edge as belonging to the initial state.

Examples

Using the setup in the CffGenerator class example:

generator = hep.CffGenerator()
generator.mark_initial_state_edge(diagram.external_edges[0].id)
result = generator.generate(diagram)

Parameters

edge (int) Diagram edge ID to classify as initial state.