Constraining supergravity scenarios through the b → s, γ decay

We evaluate the branching ratio BR(b → 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. The numerical results show some disagreements with part of the previous results in the literature, while they are in agreement with others. For minimal supergravity the CLEO upper and lower bounds put important restrictions on the scalar and gaugino masses in both cases μ < 0 and μ > 0. For the other supergravity scenarios the relevant CLEO bound is the lower one. The fact is stressed 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 the minimal supergravity scenario with μ < 0 if no discrepancy is found with the standard model prediction, while for the other supergravity scenarios analyzed there will remain low-energy windows.