Gluino contribution to radiative B decays: Organization of QCD corrections and leading order results

The gluino-induced contributions to the decay b→sγ are investigated in supersymmetric frameworks with generic sources of flavor violation. It is shown that, when QCD corrections are taken into account, the relevant operator basis of the standard model effective Hamiltonian gets enlarged to contain (i) magnetic and chromomagnetic operators with a factor of α_s and weighted by a quark mass m_b or m_c, (ii) magnetic and chromomagnetic operators of lower dimensionality, also containing α_s, and (iii) four-quark operators weighted by a factor α_s². Numerical results are given, showing the effects of the leading order QCD corrections on the inclusive branching ratio for b→sγ. Constraints on supersymmetric sources of flavor violation are derived.