On the QCD corrections to Delta F=2 FCNC in the Supersymmetric SM with hierarchical squark masses

In the context of the Supersymmetric Standard Model with hierarchical sfermion masses, we re-analyze the QCD corrections to Delta F=2 effective Hamiltonian properly including effects which have been neglected so far. The point is that some Delta F=2 diagrams, involving both the heavy and the light sparticles, exhibit a logarithmic dependence on the ratio between the two masses, signalling a sensitivity to all the momenta between the two scales. In order to properly deal with these terms one has to take into account the mixing between Delta F=1 and Delta F=2 operators. In typical situations this treatment can affect the result at the level of 30% or even more.