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

TL;DR

This paper re-analyzes QCD corrections to Delta F=2 processes in the supersymmetric standard model with hierarchical squark masses, highlighting the importance of operator mixing and the impact of logarithmic mass ratio dependencies.

Contribution

It introduces a comprehensive treatment of operator mixing and logarithmic effects in QCD corrections for hierarchical squark masses, improving previous approximations.

Findings

Logarithmic dependence on mass ratios affects corrections significantly.

Operator mixing between Delta F=1 and Delta F=2 is crucial for accuracy.

Corrections can alter results by 30% or more.

Abstract

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.