The chromomagnetic dipole operator and the B semileptonic branching ratio

Abstract

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 → X s γ) and BR( B → X s σ). 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).