This is the approach to be followed by the user who does not need any operator nor observable beyond what is already implemented in FlavorKit. In this case, FlavorKit reduces to the standard SARAH package. The user can use SARAH to obtain analytical results for the flavor observables and, if he wants to make numerical studies, to produce Fortran modules for SPheno.
SARAH can handle the analytical derivation of all the relevant Wilson coefficients in the model defined by the user. The resulting expressions can be then extracted in LaTeX form or used to generate a SPheno module for numerical evaluation. These are the steps to follow in order to use SARAH :
'''Loading SARAH ''': after starting Mathematica, SARAH is loaded via
The first choice works if SARAH has been installed in the Application directory of Mathematica. Otherwise, the absolute path to the local SARAH installation must been used.
Initialize a model: as example for the initialization of a model in SARAH we consider the NMSSM
Obtaining the LaTeX output: the user can get LaTeX output with all the information about the model (including the coefficients for the flavor operators) via<
Obtaining the SPheno code: to create the SPheno output the user should run
Thanks to FlavorKit, SARAH can also write LaTeX files with the analytical expressions for the Wilson coefficients. These are given individually for each Feynman diagram contributing to the coefficients, and saved in the folder
For the 4-fermion operators the results are divided into separated files for tree-level contributions, penguins contributions and box contributions. The corresponding Feynman diagrams are drawn by using FeynMF. To compile all Feynman diagrams at once and to generate the pdf file, a shell script called MakePDF_[$OPERATOR].sh is written as well by SARAH.
In case the user is interested in the numerical evaluation of the flavor observables, a SPheno module must be created as explained above. Once this is done, the resulting Fortrancode can be used for the numerical analysis of the model. This can be achieved in the following way:
'''building SPheno ''': as soon as the SPheno output is finished, open a terminal and enter the root directory of the SPheno installation, and create a new subdirectory, copy the SARAH output to that directory and compile it
> cd [$SPheno]
> mkdir NMSSM
> cp [$SARAH]/Output/NMSSM/EWSB/SPheno/* NMSSM/
> make Model=NMSSM
Running SPheno : After the compilation, a new binary SPhenoNMSSM is created. This file can be executed providing a standard Les Houches input file (SARAH provides an example file, see the SARAH output folder). Finally, SPheno is executed via
> ./bin/SPhenoNMSSM NMSSM/LesHouches.in.NMSSM
This generates the output file SPheno.spc.NMSSM, which contains the blocks QFVobservables and LFVobservables. In those two blocks, the results for quark and lepton flavor violating observables are given.