The chromomagnetic dipole operator and the B semileptonic branching ratio

We consider the possibility of having a large branching ratio for the decay b → sg coming from an enhanced Wilson coefficient of the chromomagnetic dipole operator. We show that values of BR(b → sg) up to ∼ 10% or more are compatible with the constraints coming from the CLEO experimental results on BR(B → Xsγ) and BR(B → Xsσ). Such large values can reconcile the predictions of both the semileptonic branching ratio and the charm counting with the present experimental results. We also discuss a supersymmetric model with gluino-mediated flavour violations, which can account for such large values of BR(b → sg).