feynlag.vertices.vertex.Vertex¶

class feynlag.vertices.vertex.Vertex(particles, coupling, vertex_type='', meta=<factory>)[source]¶

One Feynman vertex.

Parameters:

particles (tuple)
coupling (Expr)
vertex_type (str)
meta (dict)

particles¶

canonically sorted tuple of physical field symbols.

Type:: tuple

coupling¶

the full rule i × coefficient × ∏ multiplicities! (may contain p(φ) momentum tags for derivative couplings). For a multi-structure vertex (VVVV) this slot is zero and the real couplings live in meta['structures'] — read them through structure_couplings.

Type:: sympy.core.expr.Expr

vertex_type¶

catalog key ('VVS', …).

Type:: str

__init__(particles, coupling, vertex_type='', meta=<factory>)¶

Parameters:

particles (tuple)
coupling (Expr)
vertex_type (str)
meta (dict)

Return type:

None

Methods

`__init__`(particles, coupling[, vertex_type, ...])
`from_coefficient`(field_tuple, coefficient[, ...])	Build from a monomial coefficient (extractor output).
`from_structures`(ordering, structures[, ...])	Build a multi-structure vertex (VVVV).

Attributes

`lorentz_structures`
`structure_couplings`	`{lorentz name: coupling}` for ANY vertex — the multi-structure dict when there is one, else the single structure carrying `coupling`.
`structures`	`{lorentz name: coupling}` for a multi-structure vertex, else `None`.
`vertex_type`
`particles`
`coupling`
`meta`