Probing photon helicity in radiative B decays via charmonium resonance interference

We investigate a new method to probe the helicity of the photon emitted in the b→sγ transition. The method relies on the observation of interference effects between two resonance contributions, B→K∗(Kγ)γ and B→ηc(γγ)K or B→χc0(γγ)K to the same final state Kγγ. Decays of the type B→Kres(Kγ)γ dominate the B→Kγγ yield throughout most of the phase space, and may be accessible at current B meson facilities already.