Using UFO Models¶
In addition to the wide range of internal BSM models it is possible to use most models using the UFO format with Herwig. Herwig can currently only handle the perturbative Lorentz structures which arise in the coupling of particles but in most cases this is sufficient.
There are a wide range of models available in the FeynRules Model database
While many of these models contain both the UFO files need to use the model with Herwig a number only contain the FeynRules Mathematica files which can be used to generate the UFO files required by Herwig.
We will use the \(W'\) model as a simple example. The model is available here
First we need to either download the ufo file using a web browser, or directly get it using
Then extract the files
tar xzf weff.ufo.tgz
The files can then be processes to produce the C++ code needed by Herwig using the converter script supplied with Herwig
This produces a number of C++ files and an example input file. We first need to compile
the C++ code using the
Makefile which has been automatically generated
In this model as the main feature is the existence of the \(W'\) resonance instead of
using the general
HPConstructor we will use the
ResonantProcessConstructor just to
construct the resonant processes and make use of the
Inclusive option for the processes.
The can be achieved by editing the example
insert ResConstructor:Incoming 0 /Herwig/Particles/u insert ResConstructor:Incoming 0 /Herwig/Particles/ubar insert ResConstructor:Incoming 0 /Herwig/Particles/d insert ResConstructor:Incoming 0 /Herwig/Particles/dbar insert ResConstructor:Incoming 0 /Herwig/Particles/g # insert ResConstructor:Intermediates 0 /Herwig/FRModel/Particles/Wp+ insert ResConstructor:Intermediates 0 /Herwig/FRModel/Particles/Wp- # set ResConstructor:Processes Inclusive
The standard read and run can then be read to generate events
Herwig read LHC-FRModel.in Herwig run LHC-FRModel.run