Matchete`
Matchete`

DefineCouplingOrder

DefineCouplingOrder[name,couplings,hierarchy]

defines a coupling order (name) based on the given couplings. The argument hierarchy allows to define a relative hierarchy among different coupling orders. The maximum expansion order is set to 99 by default.

DefineCouplingOrder[name,couplings,hierarchy,expansionOrder]

defines a coupling order (name) based on the given couplings. The expansionOrder defines the maximum expansion order that can be considered by event generators and hierarchy allows to define a relative hierarchy among different coupling orders.

Details and Options

  • The label name must be a string, the argument couplings should be a coupling label or a list of coupling labels and can contain powers of coupling labels (or lists containing pairs of coupling labels and their integer order).
  • Defining a coupling order informs Matchete about a group of couplings that contribute to the same type of interactions. The defined coupling orders are then stored in an internal association. It is only used for numerical reasons and is given to Monte Carlo event generation tools when creating UFO files with the command ExportUFO. The arguments are therefore all similar to the UFO format. Coupling orders have no impact on any other internal Matchete functions or workflows.

Examples

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Basic Examples  (1)

Define a coupling using DefineCoupling:

  • Define a corresponding coupling order:
    • Coupling orders can be viewed with GetCouplingOrders:
    Resetting the coupling orders is achieved through:

    Neat Examples  (1)

    Load the broken Standard Model file:

    Go to the vacuum of the broken phase using ToBrokenPhase and ImplementVacuumConditions:

    Define the coupling orders for QED and QCD:

    Here we define that M, M, M, ℯ, gY, gL are order one with respect to QED, while v is order -1 and λ is of order 2 (the order is the inverse of the exponent provided above). Similarly, gs is order one with respect to QCD.
    By default, terms up to order 99 in QED and QCD are allowed.
    Two insertions of QCD couplings should be counted as one insertion of a QED coupling.

    Inspect the coupling orders:

    Equivalently, one can also define the various orders by paring the individual coupling labels with the integer order in a sublist:

    If no integer is provided, 1 is taken as default.

    Tech Notes
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  • SMEFT: Feynman Rules and UFO
    • ▪
  • From BSM to EFT: Feynman Rules and UFO