SurfacePair

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

`SurfacePair`

class SurfacePair

The two linear factors of an uncut propagator at an LTD residue.

minus represents :math:q_e^0-E_e and plus represents :math:q_e^0+E_e, with :math:q_e^0 taken from residue.energy_map. Their product is :math:(q_e^0)^2-E_e^2. Each SurfaceFactor retains its sign relative to the stored affine surface. Switching factors changes only the coefficient of :math:E_e, not the cut-edge pole assignments.

Examples

from symbolica.community import hepkit as hep
process = hep.Model.phi3().process(["phi"], ["phi", "phi"])
diagrams = process.generate_diagrams(
    loops=1, max_vertices=3, maximum_bridges=0, progress=None
)
diagram = diagrams.diagrams[0]
ltd = diagram.integrate_energy(method="ltd")
residue = ltd.residues[0]
pair = next(iter(residue.surface_pairs.values()))
denominator = pair.minus.to_expression() * pair.plus.to_expression()

Attributes

Name	Description
`minus`	The :math:`q_e^0-E_e` denominator factor evaluated at this residue.
`plus`	The :math:`q_e^0+E_e` denominator factor evaluated at this residue.

`minus`

SurfacePair.minus: SurfaceFactor

The :math:q_e^0-E_e denominator factor evaluated at this residue.

Examples

factor = pair.minus

Returns

SurfaceFactor The stored affine surface together with its occurrence sign.

`plus`

SurfacePair.plus: SurfaceFactor

The :math:q_e^0+E_e denominator factor evaluated at this residue.

Examples

factor = pair.plus

Returns

SurfaceFactor The stored affine surface together with its occurrence sign.

Methods

Name	Description
`__repr__`	Identify both denominator factors for this tree edge.
`_repr_html_`	Render the minus/plus factors evaluated at the owning residue.

`repr`

SurfacePair.__repr__() -> builtins.str

Identify both denominator factors for this tree edge.

Examples

text = repr(pair)

`_repr_html_`

SurfacePair._repr_html_() -> builtins.str

Render the minus/plus factors evaluated at the owning residue.

Examples

html = pair._repr_html_()