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b-physics

b \to s \gamma

To compute b \to s \gamma add FlexibleSUSYObservable`bsgamma into ExtraSLHAOutputBlocks block in FlexibleSUSY.m.in for a model of interest. As an example, below is the corresponding part from MRSSM2CKM

ExtraSLHAOutputBlocks = {
    {FlexibleSUSYLowEnergy, {
            {21, FlexibleSUSYObservable`aMuon},
            {23, FlexibleSUSYObservable`EDM[Fe[1]]},
            {24, FlexibleSUSYObservable`EDM[Fe[2]]},
            {25, FlexibleSUSYObservable`EDM[Fe[3]]},
            {26, FlexibleSUSYObservable`BrLToLGamma[Fe[2] -> {Fe[1], VP}]},
            {27, FlexibleSUSYObservable`bsgamma}
        }
    }
};

By default, calculation of b-physics observables is enabled only for models with a non-trivial CKM matrix. Currently, these are: CMSSMCKM and MRSSM2CKM (by convention all such model names have suffix CKM). After a normal FlexibleSUSY run you'll find in the run directory a file called WC_MODELNAME.json. This is an input to the flavio package by D. Straub. To use it, first, install flavio as expained here. In the utils directory of FlexibleSUSY there's a script calc_b_to_s_gamma.py. Call it from the directory where the .json file is located

python3 /path/to/calc_b_to_s_gamma.py WC_MRSSM2.json

This will result in an output like

BR(B->Xsgamma) =  0.0006411523880676971