The B → XSγγ rare decay

The rare decay B → XSγγ is studied in the standard model (SM) and in two different versions (Model I and Model II) of the two Higgs doublet model (2HDM). In the SM the branching ratio into hard photons is about 1 × 10−7 and can be appreciably different in the 2HDM. We also introduce a forward-backward asymmetry which gives an additional handle to discriminate different models.