Supergravity and the $b\to s,γ$ decay

Abstract

We evaluate the branching ratio BR($b\rightarrow s,γ$) in the minimal supersymmetric standard model (MSSM), determining the corresponding phenomenological restrictions on two attractive supergravity scenarios, namely minimal supergravity and a class of models with a natural solution to the $μ$ problem. We have included in the calculation some one--loop refinements that have a substantial impact on the results. It is stressed the fact that an eventual improvement of the experimental bounds of order $10^{-4}$ would strengthen the restrictions on the MSSM dramatically. This would be enough to discard these supergravity scenarios with $μ<0$ if no discrepancy is found with the standard model prediction, while for $μ>0$ there will remain low-energy windows.