= SM + anom as follows
(where SM represents the usual Standard Model Lagrangian and anom is taken
from Ref. [1]):
As of version 3.0, it is possible to specify anomalous trilinear couplings for the W+W-Z and W+W-γ vertices that are relevant for WW and WZ production. To run in this mode, one must set zerowidth equal to .true. and modify the appropriate lines for the couplings in input.ini (see below). Note that, at present, the effect of anomalous couplings is not included in the gluon-gluon initiated contributions to the WW process.
The anomalous couplings appear in the Lagrangian, = SM + anom as follows
(where SM represents the usual Standard Model Lagrangian and anom is taken
from Ref. [1]):
where Xμν ≡ ∂μXν - ∂νXμ and the overall coupling factors are gWWγ = -e, gWWZ = -ecotθw. This is the most general Lagrangian that conserves C and P separately and electromagnetic gauge invariance requires that there is no equivalent of the Δg1Z term for the photon coupling.
In order to avoid a violation of unitarity, these couplings are often included only after suppression by dipole form factors,
where ŝ is the vector boson pair invariant mass and Λ is an additional parameter giving the scale of new physics, which should be in the TeV range. These form factors should be produced by the new physics associated with the anomalous couplings and this choice is somewhat arbitrary. The use of the form factors can be disabled as described below.
The file input.ini contains the values of the 6 parameters which specify the anomalous couplings. If the input file contains a negative value for the form-factor scale then the suppression factors described above are not applied.
[1] L.J. Dixon, Z. Kunszt and A. Signer, Vector boson pair production in hadronic collisions at order αs : Lepton correlations and anomalous couplings, Phys. Rev. D60 (1999) 114037 [hep-ph/9907305].