Predictions for b -> ssdbar, ddsbar decays in the SM and with new physics

Understand

The b -> ssdbar and b -> ddsbar decays are highly suppressed in the SM, and are thus good probes of new physics (NP) effects.

• We discuss in detail the structure of the relevant SM effective Hamiltonian pointing out the presence of nonlocal contributions which can be about \lambda^{-4} (m_c^2/m_t^2) ~ 30% of the local operators (\lambda = 0.21 is the Cabibbo angle).
• The matrix elements of the local operators are computed with little hadronic uncertainty by relating them through flavor SU(3) to the observed \Delta S = 0 decays.
• We identify a general NP mechanism which can lead to the branching fractions of the b\to ss\bar d modes at or just below the present experimental bounds, while satisfying the bounds from K-Kbar and B_{(s)}-Bbar_{(s)} mixing.