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 X_{μν} ≡ ∂_{μ}X_{ν} - ∂_{ν}X_{μ} and the overall coupling factors are g_{WWγ} = -e,
g_{WWZ} = -ecotθ_{w}. This is the most general Lagrangian that conserves C and P
separately and electromagnetic gauge invariance requires that there is no equivalent
of the Δg_{1}^{Z} 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
α_{s}
:
Lepton
correlations
and
anomalous
couplings,
Phys.
Rev.
D60
(1999)
114037
[hep-ph/9907305].