While SARAH can create valid SPheno code for many different models, there are some requirements on the model and some minor restrictions on the functionality of the resulting SPheno module. At the moment, those are
Fit to low energy data: in order to perform a fit to low energy data (e.g. for fermion masses, mZ, GF and αe**m) as starting point of the RGE evaluation, the following parameters must be present in the model
SM Yukawa couplings for lepton and quarks
One or two Higgs doublet VEVs
the three SM gauge couplings and the SM particle content.
These are used as explained here to obtain the running parameters. However, there are some attempts to relax this conditions, see
In addition, there is still the option to use the option to generate a low scale SPheno version which performs no RGE running and no automatic matching to the SM parameters, and which is therefore more flexible.
Flavor decomposition: with SARAH it is possible to assign a unique name to each generation of a particular field and this way treat the individual generations as independent fields, see Flavour Decomposition. That is not yet supported in the SPheno output.
NoFlavorMixing': Mixing matrices generated with the option NoFlavorMixing can not yet be handled by the numerical code.